Thanks for the pointer to the other thread TerraMex, I found some good info there, and have just posted an extensive reply on that thread. Unless this thread really takes off, I'll probably try to move most of my discussion over there.
I appreciate the suggestion redleader, it's a good one. I'm planning to home-make as much of this setup as I can though - since I'm currently unemployed I have the time, it's a good learning and practicing experience, and since I already have most of the tools, it will probably be cheaper.
(I can get copper plates and blocks for $4.80/lb, and a roll of copper tubing isn't very much at the local hardware store)
Gooserider