hey! welcome to the site!
hm to start off, i have a kitten, one bp, and a red tailed boa. recently i just changed to sterilite tubs for the two enclosures and its been working great. i'm guessing your corns are in glass aquariums which in my opinion when you get a bp you should shop for tubs or if you have the extra cash one of those animal plastic t3s, i hear such good things and love the look. the temps and humidity requirements are a little bit harder for balls than for corn snakes as i'm sure you've noticed. so far i've had no problem with the kitten in regards to the ball. when i'm not home i close the door to the room that the snakes are in and if i take them out ever i keep the cat out of the room. if the snakes can't get out (which they never should) then your cats will be fine, i'd keep them away or out of reach in case the cats stress out the bp if they're constantly pawing and hitting the enclosure though it seems like you've nipped that at the bud.
i heat with one UTH under one side on each of the enclosures. i'd recommend to get an Acu-rite thermometer (available at walmart for about $10- great deal) which are accurate and pretty easy to fix if they are being wacky, they have a probe that you put on the hot side and the cool side and humidity base is placed on the cool. i'd recommend heating with the pads still and they're fairly easy to hook up to t-stats to control the temp. output or a dimmer if you have a room that is constant in temps and you don't mind checking a couple times a day (though thermostats will never go wacky if the power goes crazy and heat up extreme, they are a safeguard)
maybe just get a pair of metal tongs because they're fairly cheap and a good investment, gives you quick peace of mind and they'll last.
you could always heat with flexwatt which i believe is pretty cheap and tons of people use here. i used a lamp before with a red light that was on constantly to maintain temps and i just found lots of problems with controlling humidity and also i had a glass aquarium at the time. good luck with getting a bp! they're awesome, addicting, gorgeous, and a great snake all around.