If i d/l files from p2p from multiple computers, can i complete an incomplete d/l on one pc from another pc?

Answer 1

No because your pc will read it as two separate downloads, in other even if it has the same name; its still two separate files. Thus it will try and download the entire file from both computers.

Answer 2

You don't say what p2p system you are using, but with WinMX or BitTorrent this is certainly possible. The files must be 100% identical for it to work.