[JFreak]

Cost-effective way to expand your possibilities would be the Focusrite Octopre Dynamic MkII which connects to your system via ADAT and gives you 8 more preamps of decent quality.

The analog compressors connect to your 003 via analog TRS cables. On the PT mixer window, choose hardware insert (i/o) from the insert menu. You need to understand that hardware inserts need to use matching i/o numbers, so if you go out from analog output 8 you need to come back from analog input 8 as well. It's all there in the i/o setup, learning this shouldn't be very hard... good luck!