I plan to download and install Ubuntu 13.04 and I would like to have two compilers on my system.

First question: what is the version of gcc/g++/gfortran shipped with ubuntu 13.04 ? (is it 4.7.3 ?).

So, I would like to have gcc/g++/gfortran 4.8 as my default compiler (and 4.7.3 as a "backup"). Is there a well precompiled version avaible somewhere (compiled with the right optimizations and enabling std::thread) ? And how to download on install it ?