They are all unbalanced -10db RCA jacks. 8 in and 8 out. Well, there's the ADAT optical I/O, too.
Last time I had one, I just bought a bunch of high quaity 1/4" to RCA cables and hooked them up to the unbalanced outputs of my gear. I'm not quite sure how you'd use it with balanced gear or +4db level stuff, though I'll have to figure that out for hooking it up to the 002.
For the digital I/O, you just get ADAT optical cables (TOSLINK, I think) to go back and forth. So your mixer or preamps will go into the ADAT's RCA inputs, the signal goes out through the optical to the 001, and if you want to use the 001's ADAT channels for outboard mixing, they'll go back out the optical to the adat, and out it's RCA outputs to your gear. That's what I was told, at any rate. I didn't have digital I/O when I last had an ADAT.
Take care,
Chris