A ".bin" file is a binary file. The extension is generally used to make sure IE downloads stuff right. (If you're using Safari, it's pretty smart about all file type issues.) An incomplete download would probably give Stuffit trouble.
I'm not clear from your message....are you having trouble downloading Apple's Developer Tools, or the PRC-Tools from
http://sidewww.epfl.ch/~crivelli/prc...download.html?
You can get the Apple Developer Tools from a couple of different spots on Apple's site (Mac OS X, ADC, Software) and it might even be in the Software folders of your dot Mac account.
You need Apple's Developer Tools to get the basic things like GCC (C compiler), make, and so on. PRC adds a few things on top of the Apple Developer Tools: the GCC compiler that produces 68000 code, tools to generate Palm resource files and to link it all together, etc.