They're so cute when they're that tiny

For your questions:
false, true, false.

They do well at lower temps that ball pythons, but a uth provides a heat gradient, and I have often seen corn snakes make use of UTHs. Look up some care sheets to get good temps for a warm spot, and set up a rheostat or thermostat with your UTH to achieve the desired temp. I have often seen corns kept on newspaper/paper towel actually bury under the towel to get closer to the UTH seeking warmth so make sure you set the UTH to a temp that isn't too hot.

Corn snakes are master escape artists. They don't push as hard as BPs, but a large corn can lift a certain amount of weight, and they don't have to lift very far to escape since they are so skinny.

No extra humidity necessary, I have never seen a corn that had a bad shed due to low humidity, never needed to mist corns when they go into shed to "help" them. If you're in a desert or somewhere with literally 0% humidity all the time, an extra wide water bowl might be nice to have just in case , I have no experience with corns at literally 0% humidity, but they do perfectly fine in indoors Minnesota, and believe me it gets dry here.