what should i mixdown to for highest possible quality back to...
mini-dv tape? (uncompressed avi??)
burning to cd-r's. I can't seem to find a way to just make it get the highest quality for whatever length project, to fit in 700MB (or whatever CD-R size i have)...is there a way to do this?
An .AVI file is merely a container, it can contain video compressed with a variety of different codecs. Some codecs look very good, some don't. There is always a trade-off between filesize and quality. Generally speaking, for highest quality at a reasonable file size, you should probably use an AVI file compressed using the Sonic Foundry DV codec, particularly since your final destination is recording back to a DV camcorder.
DV video is about 225 meg/minute and you can fit about 3 minutes and 16 seconds of DV video on a 700 meg, "80-minute" CDR.
You could also use a file-splitting utility to break your video file into CDR-sized chunks. One free file splitter is called HJ-SPLIT and can be downloaded from www.freebyte.com
I personnaly use Winrar to archive my projects, it'll split the files and compress them in lossless manner. I usually get good rations, 900 megs will give 600 megs once rared.