Ah, if you can get another one for free, you'll have to hook me up!
I'll extend an extra special welcome to Navy personel: Airspirit used to be a Navy man too.
Back to work...
For the rads, personally, I didn't put a lot of effort into selecting one, other than going through the database to pick one that was exactly the size I needed, and as thick as possible. If you want details on the whole runs/pass question, we covered it
here (I think).
For the pump, you're not really going to need anything bigger than what you have now. If you want to do a proof-of-concept, you might consider running two of those pumps in series, then later upgrade to the Iwaki. But if you're about 2/3 of the way on this 3'000 budget, you're doing very well, and the Iwaki should fit.
For the tubing, I'm still a little confused as to why you need any external run of pipes. Otherwise, you might be in for a shock, when you find out the actual measurements of the copper and PVC parts: "1/2" copper piping isn't 1/2", inside or out!
www.mcmaster.com has the specs on the actual measurements, but a trip to Lowes with a ruler always helps.
For clear tubing, the above link, or USplastics.com have them, in either polycarbonate or acrylic. There's a couple more links floating around these forums, I'm sure someone will pitch in (right?
).