You can move them from within µTorrent to your external drive with the advanced option of download location. That way, µTorrent keeps track of the location (stop that torrents before disconnecting the external drive) and you can continue to seed or easy restart seeding (aka reseed).
thanks! I didn't know this either. Helpful.
I just finished the most recent three of this new arc of six (?) - I like the characters so much that I find it a bit hard to be too critical. One thing I really like about the new series is seeing all Midnighter's friends (and tricks) - they are an interesting corollary to The Authority and pose a thoughtful response to the question of whether a superhero could have friends who aren't superheroes.