I'm using Transmission for BTs.
As far as audio software goes, I use FeltTip's Sound Studio. Tried a couple of options (Amadeus, Audacity, etc. . .) and just liked the interface and usability of SoundStudio best. They do offer a healthy fully-functional trial period as well.
After I made the jump, bought an R-4 and moved into 4 channel recording, I had to find something with a little more under the hood. Picked up a copy of Logic Express and am pretty impressed with it thus far. I am still using SoundStudio for tracking.
-jay