Any text editor can be used to hack the code. Everyone has their favourite so I'm not going to suggest one or everyone will jump on me. As for a compiler use the Gnu C Compiler, obviously
http://gcc.gnu.org/ . Unfortunately it's a bit of a chicken and egg situation with that, before you can compile it from the code you need to already have a working C Compiler. If you don't have one you should install it with .RPM or whatever. If you do compile it yourself, use the option ./configure --enable-languages=c,c++ or it'll take ages (like 40 minutes) if you make bootstrap and build it with all the languages it can compile. Unless you need to compile Fortran and Java or whatever