best of luck with the FT client (no offer of help from me as the last time I coded was about 4 lines of Basic on a BBC-B).
One question: will you be including IP bouncing?
it seems far too easy right now for some 'copyright enforcer' to run an IP trace by d/ling a file from you (leading to nasty 'cease & desist' letters to people's ISPs) and apparently
Filetopia has managed to combat this with IP bouncing.
I think end-to-end anonymity is becoming a big concern for p2p users, and would look forward to an FT client that could provide that.