Can you tell me: could I use twisted for p2p-applications creating? And what protocols should I choose for this?
The best solution is to use the source code for BitTorrent. It was built with Twisted until they switched over to a C++ implementation called Utorrent.
As an alternative, you also might want to take a look at Vertex.
It is a p2p library built on top of Twisted and comes with goodies like bypassing firewalls.
Its probably more complete than the other people's sample.