Moving multiple toons is pretty much the most difficult obstacle facing anyone trying to simultaneously control them, so heavy use of /follow combined with another key bound to strafe (or backup etc) only on your alt will allow you to break follow on your 2nd toon to cast etc while still moving with your main, you'll find yourself beginning to be able to gauge /follow range (10-12yds?) very quickly.

Sounds like you pretty much have the gist of it though. One thing I like to do when leveling/instance grinding etc is to keep the fights mobile, move my toons as though I am PvPing and such (obviously not practical in all scenarios). If I don't do this I find that my reflexes/timing lapse into a PvE mode which is totally different than PvP.