Will DebTorrent download all the packages in the archive?
From version 0.1.2 on, DebTorrent listens for requests from APT for packages to download. When you do an apt-get install foo, APT will send a request for foo to DebTorrent, which will download that package only. Once that package is complete, DebTorrent will stop downloading (but will continue to upload foo and any others to peers).