1)To get the Android source code from Google repo, follow the steps below:
$ cd ~
$ mkdir myandroid
$ mkdir bin
$ cd myandroid
$ curl http://commondatastorage.googleapis.com/git-repo-downloads/repo > ~/bin/repo
$ chmod a+x ~/bin/repo
$ ~/bin/repo init -u https://android.googlesource.com/platform/manifest -b android-4.4.3_r1
$ ~/bin/repo sync # this command loads most needed repos. Therefore, it can take several
hours to load.
But after giving the final step it took almost of 2 days to download and is not giving any confirmation.
2)Is it necessary to have 12.04 version(64 bit) os?? I am using 12.04 version (32-bit) of ubuntu.