In fact, it rather gives the impression that the nightlies are only relevant to the Windows version of Code::Blocks. Firstly, I assume this probably isn't true??
It's mostly true; other people provide packages for a few major Linux distros.
Secondly, I'd like to get to the stage of building C::B from source. Can Code::Blocks be downloaded as a C::B project? If so, where from?
Yes; Subversion. See the
Source Code page.