I gotta admit that you sound like you dont know much about cars and are about to get majorly screwed. But thats just my opinion.
Are you absolutely sure you'll be getting everything you need for the swap at once? Wiring harness, side mount intercooler, igniter chip, ecu, MAFS etc...? You'll probably need to upgrade the fuel pump and worry about the wiring the most. Also what SR20DET are you getting? S13,14,15? Here are some sites that may be able to help you...
http://sr20.hybrids.jp/http://www.euros ... chinfo.asp <<this is useful because it has the FSM's for the SR20DET and CA18DEThttp://
www.eurostreetgraphics.com/srswap.htm
These should be somewhat useful, read up! And if youve already seen all these sites, perhaps your more prepared than I thought you were.