Hi, you're welcome!
To answer your questions (as far as I could):
Gnutella protocol is full IP based (IPv4 yet), not hostname based. I don't think that Gnutella is designed for static networks, actually itself has a very dynamic structure! Disapearing hosts and too simple programmed retry attempts are causing this annoyance IMHO. There is allready a new BYE-descriptor in development, which hopefully decreases the unwanted connects. But I think further investigations and a rety with more AI (intelligence) would be appreciated. If you want to talk with other Gnutella client developers, subscribe to the_GDF mailinglist - or just use the Development Forum here. The GDF is linked in the sticky thread in the Development Forum,
klick here.
Netbios is AFAIK typical for script kiddies trying to find a (MS Windows) vulnerabity on your PC. Better use a packetfilter or better firewall concept when being online.
Greets, Moak