Unity 4.6 Editor, Create a Script with Predefined Data

Try this out

Put the CharacterCreatorEditor.cs in a folder named Editor somewhere in your project.

CharacterCreatorEditor.cs

using UnityEngine;
using System.Collections;
using UnityEditor;
using System.IO;
using System.Text.RegularExpressions;

public class CharacterCreatorEditor : EditorWindow {

    #region Character Fields
    //Add as many character specific fields / variables you want here.
    //Remember to update the same thing in the "CharacterTemplate.txt"!
    public string characterName = "John Doe";

    public float characterHealth = 10;

    public int characterCost = 1000;

    public bool isBadGuy = false;
    #endregion


    private bool needToAttach = false;      //A boolean that checks whether a newly created script has to be attached
    private float waitForCompile = 1;       //Counter for compile
    GameObject tempCharacter;               //A temporary GameObject that we assign the new chracter to.


    //A Menu Item when clicked will bring up the Editor Window
    [MenuItem ("AxS/Create New Character")]
    public static void CreateNewChar () {
         EditorWindow.GetWindow(typeof(CharacterCreatorEditor));
    }


    void OnGUI () {

        GUILayout.Label("Here's a sample Editor Window. Put in more variables as you need below.");
        GUILayout.Space(10);

        //Note on adding more fields
        //The code below is broken into groups, one group per variable
        //While it's relatively long, it keeps the Editor Window clean
        //Most of the code should be fairly obvious

        GUILayout.BeginHorizontal();
        GUILayout.Label("Character Name", new GUILayoutOption[0]);
        characterName = EditorGUILayout.TextField(characterName, new GUILayoutOption[0]);
        GUILayout.EndHorizontal();
        GUILayout.Space(10);

        GUILayout.BeginHorizontal();
        GUILayout.Label("Character Health", new GUILayoutOption[0]);
        characterHealth = EditorGUILayout.FloatField(characterHealth, new GUILayoutOption[0]);
        GUILayout.EndHorizontal();
        GUILayout.Space(10);

        GUILayout.BeginHorizontal();
        GUILayout.Label("Character Cost", new GUILayoutOption[0]);
        characterCost = EditorGUILayout.IntField(characterCost, new GUILayoutOption[0]);
        GUILayout.EndHorizontal();
        GUILayout.Space(10);

        GUILayout.BeginHorizontal();
        GUILayout.Label(string.Format("Is {0} a Bad Guy?", new object[] { characterName }), new GUILayoutOption[0]);
        isBadGuy = EditorGUILayout.Toggle(isBadGuy, new GUILayoutOption[0]);
        GUILayout.EndHorizontal();
        GUILayout.Space(10);

        GUI.color = Color.green;

        //If we click on the "Done!" button, let's create a new character
        if(GUILayout.Button("Done!", new GUILayoutOption[0]))
            CreateANewCharacter();

    }

    void Update () {
        //We created a new script below (See the last few lines of CreateANewCharacter() )
        if(needToAttach) {

            //Some counter we just keep reducing, so we can give the
            //EditorApplication.isCompiling to kick in
            waitForCompile -= 0.01f;

            //So a few frames later, we can assume that the Editor has enough
            //time to "catch up" and EditorApplication.isCompiling will now be true
            //so, we wait for the newly created script to compile
            if(waitForCompile <= 0) {

                 //The newly created script is done compiling
                if(!EditorApplication.isCompiling) {

                    //Lets add the script
                    //Here we add the script using the name as a string rather than
                    //it's type in Angled braces (As done below)
                    tempCharacter.AddComponent(characterName.Replace(" ", ""));

                    //Reset the control variables for attaching these scripts.
                    needToAttach = false;
                    waitForCompile = 1;
                }
            }
         }
    }

    private void CreateANewCharacter () {

        //Instantiate a new GameObject
        tempCharacter = new GameObject();

        //Name it the same as the Character Name 
        tempCharacter.name = characterName;

        //Add the ChracterScript component. Note the use of angle braces over quotes
        tempCharacter.AddComponent<CharacterScript>();

        //Loading the template text file which has some code already in it.
        //Note that the text file is stored in the path PROJECT_NAME/Assets/CharacterTemplate.txt
        TextAsset templateTextFile = AssetDatabase.LoadAssetAtPath("Assets/CharacterTemplate.txt", 
                                                               typeof(TextAsset)) as TextAsset;
        string contents = "";
        //If the text file is available, lets get the text in it
        //And start replacing the place holder data in it with the 
        //options we created in the editor window
        if(templateTextFile != null) {
            contents = templateTextFile.text;
            contents = contents.Replace("CHARACTERCLASS_NAME_HERE", characterName.Replace(" ", ""));
             contents = contents.Replace("CHARACTER_NAME_HERE", characterName);
            contents = contents.Replace("CHARACTER_HEALTH_HERE", characterHealth.ToString());
            contents = contents.Replace("CHARACTER_COST_HERE", characterCost.ToString());
            contents = contents.Replace("CHARACTER_BAD_GUY_HERE", isBadGuy.ToString().ToLower());
        }
        else {
            Debug.LogError("Can't find the CharacterTemplate.txt file! Is it at the path YOUR_PROJECT/Assets/CharacterTemplate.txt?");
        }

        //Let's create a new Script named "CHARACTERNAME.cs"
        using(StreamWriter sw = new StreamWriter(string.Format(Application.dataPath + "/{0}.cs", 
                                                           new object[] { characterName.Replace(" ", "") }))) {
            sw.Write(contents);
        }
        //Refresh the Asset Database
        AssetDatabase.Refresh();

        //Now we need to attach the newly created script
        //We can use EditorApplication.isCompiling, but it doesn't seem to kick in
        //after a few frames after creating the script. So, I've created a roundabout way
        //to do so. Please see the Update function
        needToAttach = true;
    }

}

Put the below text file into the path "YOUR_PROJECT/Assets/CharacterTemplate.txt" If you don't, the code WON'T WORK!

CharacterTemplate.txt

using UnityEngine;
using System.Collections;


public class CHARACTERCLASS_NAME_HERE : MonoBehaviour {

    public string characterName = "CHARACTER_NAME_HERE";

    public float characterHealth = CHARACTER_HEALTH_HERE;

    public int characterCost = CHARACTER_COST_HERE;

    public bool isBadGuy = CHARACTER_BAD_GUY_HERE;


    public void SomeMethod () {

    }
}

Explanation of the code

First, the editor script takes all the input variables (should be fairly obvious what they are) Once you click the done button, the following happen

1. A new GameObject is Instantiated
2. The instantiated GameObject is named the same as the Character Name in the Editor (eg. John Doe)
3. The CharacterScript (your common script) is attached
4. The template text file ("CharacterTemplate.txt") is read, and all the data is replaced with the data you entered in the Editor Window
5. This is then written to a new script file
6. We refresh the Asset Database, and wait until the newly created script is compiled (eg. JohnDoe.cs)
7. Lastly attach the script to the GameObject instantiated in Step 1

For your second question, what you'll need to do is to have all your PlayerNamedClass extend the same base class. This way, you can type the variable you'll expose in CharacterScript

So, for example, if you call the base class "NamedCharacterScripts"

In JohnDoe.cs

public class JohnDoe : NamedCharacterScripts

In JaneDoe.cs

public class JaneDoe : NamedCharacterScripts

In CharacterScript.cs

public NamedCharacterScripts namedCharacterScript;

void Awake () {
    //This will assign JohnDoe.cs for the GameObject named "John Doe" &
    //JaneDoe.cs to the GameObject named "Jane Doe"
    namedCharacterScript = GetComponent<NamedCharacterScripts>();
}

Hope this answers your questions. If you have trouble, just leave a comment

My script is not production-ready like Venkat's answer, but it should be easier to understand for educational purposes.

using UnityEngine;
using System.Collections;
using UnityEditor;
using System.IO;

[ExecuteInEditMode]
public class CharacterTools : MonoBehaviour
{
    [SerializeField, HideInInspector]
    private string className;

    private bool waitForCompile = false;

    private void Update()
    {
        if (string.IsNullOrEmpty(className))
            return;

        if (waitForCompile && EditorApplication.isCompiling)
            waitForCompile = false;

        if (!waitForCompile && !EditorApplication.isCompiling)
        {
            var gameObject = new GameObject(className);
            Debug.Log("Attempting to add " + className);
            var c = gameObject.AddComponent(className);

            className = null;
        }
    }

    [ContextMenu("Create character")]
    private void CreateCharacter()
    {
        string name = "Number" + Random.Range(0, 100).ToString();

        string nameTemplate = "{0}Character";
        string contentTemplate = @"using UnityEngine;

public class {0} : MonoBehaviour
{{
}}
";

        var className = string.Format(nameTemplate, name);
        var path = Application.dataPath + "/" + className + ".cs";

        var scriptFile = new StreamWriter(path);
        scriptFile.Write(string.Format(contentTemplate, className));
        scriptFile.Close();

        AssetDatabase.ImportAsset(path, ImportAssetOptions.ForceSynchronousImport);
        AssetDatabase.Refresh();

        this.className = className;
        this.waitForCompile = true;
    }
}

Usage:

1. Add this script to any object on scene.
2. Right click on just added component in inspector.
3. Choose “Create character”.
4. Wait few seconds.