Hi and welcome to the forum.
Congrats on your pacman frog. I bet he/she is adorable. Yeah, you can cut the worms up into smaller pieces to feed your frog if they will take them. Worms are far more nutritious than crickets anyways. I would also recommend dubia roaches as one roach is the nutritional equivalent to five crickets. They don't stink, bite, or make noise. Not sure about the eye rule.
I suppose an UTH heater on the side would be fine, but I would personally use a low wattage ceramic bulb with a lamp that has a dimmer for your tank. Maybe 40 - 60 watt. Never put a heat mat underneath as it can burn your frog since they burrow.
Plus with ceramic bulbs you can keep them warm at night and not disturn them as ceramic bulbs put off not light. Just make sure the socket is porcelain.