Munchkin Cthulu Help Please!

[masterstatus]

I have two questions, I'm not sure if they were answered yet but I skimmed through the posts and could not find exactly what I was looking for.

1. If I draw a Cultist as a Class card at the beginning or at any other point in the game do I HAVE to play it? Or can I just keep it in my hand? If so can I discard it or give it away if I end up with 5 cards in my hand?

2. In combat if my level is equal to that of a monster do I kill it? If I don't do I at least defeat it? And if I do defeat it do I get treasure? The manual confused me a bit on this one.

Thanks in advance guys and sorry if this was already posted!