I thought it might be useful for people like myself who don't know a lot about torrents to explain things that can cause difficulty in downloading.

For example, at the moment, most of my downloads are stalling. I have a feeling that router in my area is firewalled, which could mean that people I am downloading from cannot download from me, which would class me as a freeloader in their books. Is this correct? I think maybe I'm being cancelled by the seeders for this reason.

I'm using 2.0.1 as packaged for ubuntu.

You should upgrade to 2.0.2, there are some issues with 2.0.1