Building Android source code on Ubuntu

I'm trying to build the Android source code, I followed the instructions from here: https://source.android.com/source/initializing.html

I'm using Ubuntu:

Linux user-Ubuntu 3.11.0-15-generic #25~precise1-Ubuntu SMP Thu Jan 30 17:42:40 UTC 2014 i686 i686 i386 GNU/Linux

I have 2 questions (and problems):

1. When I run 'lunch' command and choose option number 14 (aosp_hammerhead_userdebug) I get this line many times:

/bin/bash: prebuilts/gcc/linux-x86/arm/arm-linux-androideabi-4.7/bin/arm-linux-androideabi-gcc:cannot execute binary file

and then:

============================================
PLATFORM_VERSION_CODENAME=REL
PLATFORM_VERSION=4.4.2
TARGET_PRODUCT=aosp_hammerhead
TARGET_BUILD_VARIANT=userdebug
TARGET_BUILD_TYPE=release
TARGET_BUILD_APPS=
TARGET_ARCH=arm
TARGET_ARCH_VARIANT=armv7-a-neon
TARGET_CPU_VARIANT=krait
HOST_ARCH=x86
HOST_OS=linux
HOST_OS_EXTRA=Linux-3.11.0-15-generic-i686-with-Ubuntu-12.04-precise
HOST_BUILD_TYPE=release
BUILD_ID=KOT49H
OUT_DIR=out
============================================

Is it ok? and if not, what do I need to do?

2. Then I run "make" command and I get (again) the line:

/bin/bash: prebuilts/gcc/linux-x86/arm/arm-linux-androideabi-4.7/bin/arm-linux-androideabi-gcc:cannot execute binary file

and then:

Checking build tools versions...
************************************************************
You are attempting to build with an unsupported JDK.

You use OpenJDK but only Sun/Oracle JDK is supported.
Please follow the machine setup instructions at
    https://source.android.com/source/download.html
************************************************************
build/core/main.mk:152: *** stop.  Stop.

I installed open-jdk as written in the instruction. Which Java do I need to install instead? (what is the name of the package in apt?)

Thanks