porting GCC & GCC backends

[max blomme]

I'm attempting to port GCC to our companys 32bit microprocessor, and I'm 
a bit overwhelmed.

Looking through some of the documentation (there's quite a lot of it!) I 
can't seem to find the answers to a few questions.  Pardon me if they 
seem basic and obvious.

We already have an assembler and linker for the processor.  Should I (or 
can I) use them as the back end of GCC?  If I do use them, can I use the 
GCC debugger (or binutils or wherever the debugger that is tied to GCC is)?

If I cannot use our current assembler & linker, is there any 
documentation for porting GAS (I've looked and I can't seem to find any)?

The processor has a relocateable object loader in it's internally ROMed 
BIOS which I'd prefer to use, but it's a proprietary format that, as far 
as I know, does not conform to any previous standard.  The loader is 
extendable, buy bootstrapping in another loader.

In the port for GAS, can I describe this format?  Or do I need to write 
a back end to convert it's output to our format, or write another loader?

If I'm posting to the wrong list, please point me to the correct one.

Max