My cat tries to stand on all fours on my legs backwards with his hind facing me.

Is this a problem? Cats do all sorts of balancing acts like this.

Mine used to pounce on my feet off the dresser.

Notice how cats drape themselves on porch railings? Your legs are the same idea. I just kick mine off. I don't like anything sleeping on top of me (LOL). My dog learned to sleep next to the wall but my cat tries the same thing night after night.

One of mine likes to curl up and knead my armpit before burying his face there to sleep. Another will only sleep on me if I'm on my stomach and she can lie on my back.

Cats are weird. They do weird things. They sleep in weird places and positions. If it bothers you, then just move your legs until he falls off.

Cats are weird and they all like to do their own little things.