Funny, I thought those were in the FAQ, but no. So...
Void summoning is very different from the rest of the game. Only the Ryleh Priest-types (and a national hero) can do it effectively, but they still have a 5% (IIRC) chance of insanity each turn, or each summon, or something. And any astral mage - sacred or not - may get attacked, so set the immobile summons to guard him.
Normal summons never attack their creator unless specifically mentioned, as with Ashen Angels or Horrors - so spill all the blood you want.
There is no "Disband" command, but units are easy to kill in Dominions... =) I always like free militia events IFF I have a commander with enough leadership nearby to cart them to the front, or if I am playing some sort of mod that makes them cheaper (lower maintenance) while also giving them fun and clever descriptions. Can't think of any off the top of my head, though.
Edit: Wait a second,
here 's one!
