In my opinion hands down the most important thing for your friend to pick up would be a thermostat for the UTH. Dimmer switches are not a bad idea, but UTH's are notorious for spiking for no reason causeing possible medical issues for the little guy or girl.

As far as tank size goes, i started ot with a 55 gallon tank because it was my old fish tank, i jsut pit a lot of climbing limbs and vegitation in there so there were plenty of places to feel cozy for mine. So if she has a 20 thats great, less money spent down the road.

Other then that your list is pretty good..

Another important thing on your end to ensure the safty and care of your baby with your friend. Have him or her setup the whole tank and do a "dry run" period for like a week and check to make sure her temps are maintained consistently and and humidity is kept consistent as well. That was a HUGE help to me to not have a snake to worry about while working out methods to ensure her living situation is the best it can be. And it will be a great learnin experience for your friend, cause im sure you will come up with situations where you can give some tips or tricks from your experiences to your friend.