pullinteef: I run until the battery dies, which is around 35 minutes for an 8Ah pack.
This is my setup so you can see how things are mounted. Temps are never any higher than 150*F on anything. I've since geared down because ~55mph on a track is a little tough to control.
streetracer: I'd stick (no pun intended) to thermal epoxy. I don't know how well the putty transfers heat, and if it is conductive (you don't want this).