First: yes you have various external audio things for the dsp you can connect on it's port. I think they are called FA4 or FA8 or something. Also it's possible to have a 48KHz/44.1KHz sampling clock on there. Then you can just use the falcon's normal mini-jack sampler.
About the processing side: yes you can set the falcon's SDMA to record. If the datastream is slow (mostly with audio) the dma is fast enough.
The compression sounds hard to me. As of yet people have managed realtime mp2/mp3 playing on the falc. But mp2/mp3 compression is _way_ more costly. If you can pull this off people will get on their knees and worship you for years to come ;)
hope this gives you enough info. About the other postings. Indeed dspdit/qdsp are good choices, but I can also reccomend DSP debugger by Brainstorm. It has an online manual, a good GUI that allows you to peek at all of the regs/interfaces and memory of the 56001.
