Do we get the source files?

Source code isn't a panacea. It's difficult to work with someone else's code. Especially when you have to do it in your free time, which isn't always available.

That's true, but most likely the source code will have comments (considering that the game was created by a team of coders, there should be comments, but if they used corporate software, then the comments will contain nonsense like "!! fixed/added by Ivan Ivanov 03/02/2005, log #12 dated 03/02/2005")... and it's much easier to work with such code than with disassembled code.