And then if I host one, how do I boot people?
You can't do either. You can be the host, but only if they can't put you in another session and you still can't pick the map.
Not really useful to host if you can't pick the map.
Did this used to be an option? I think I saw it on the epic forums.
U can host a custom game and start on lvl 26 on Nowhere, so if u r just after the ach. that is the best way.