First Thoughts: AirPort Extreme Base Station - The Unofficial Apple Weblog (TUAW)
RE: torrenting and ports, if you have Azureus, you don't have to manually forward ports anymore with the new router. Goto Azureus Preferences > Plugins > UPnP > NAT-PMP and enable it.On the new Extreme, goto Internet > NAT and Enable NAT Port-Mapping Protocol
Now everytime you open Azureus, it should be able to open the appropriate ports on the Extreme as needed.