Hi,
I have added 1), 2) and 4) to the bug and feature request list.

3)
In general a host cache is a server which accepts connections of gnutella clients and disconnects after delivering some ip addresses of other clients being currently online.
Then your client tries to establish connections to these clients to get connected to the Gnutella network.
Therefore, a host cache is usually the entry point to the Gnutella network. The more host caches exist the better for the Gnet. (there are other strategies to get connected but this is the most important one).
That's the reason why I have decided to implement a host cache with Qtella.

The Qtella HostCache listens by default on port 6347 and acts like a real host cache. It collects ip addresses of other clients while you're connected to the Gnet and delivers them to clients which connect to port 6347.
Of course, a host cache doesn't make sense for ordinary users who are not online 24h/d and do not own a static ip. These users may disable the HostCache.