Wecome to the forum! You are getting great advice from Mark and Heather.
1. Yes, paper towels are ok for quarantine. Because Pacs are kept solitary, quarantine periods are mostly to watch for Chytrid. Pacmans do become stressed easily and will often stop eating when they are stressed. Moving to a new enclosure is stressful for them, so you want to make it as smooth as possible. And yes, you Will know when they poop! :-)
2. I also use Reptisafe. It is a good and reliable product. If you do use well water, you should test it first. Water that may be perfectly safe for you to drink may not be healthy for a Pacman. They absorb whatever is in the water through their skin, so if there is anything harmful in the water it could cause the frog to Tox-out (which will lead to death). I have seen this situation before, where people assumed that well water was automatically safe and the Pacman died. Always err on the side of caution.
3. Because these frogs burrow, they will often uproot plants. Like Heather said, wimpy plants won't make it. Please remember that they are agressive eaters. They lunge at their food and will often get bits of substrate or plants in their mouth. You don't want them swallowing anything that will cause impaction (severe constipation). This is one reason to be very cautious about moss. Some people use sphagnum moss because it helps maintain humidity, but it frequently causes impaction. Live plants also require different lighting. Unless you are set on having a live vivarium, it might be easier to start out with fake plants. Coco fiber, a couple of fake plants for the frog to get shade and burrow under, and background covering three sides of the enclosure are all it takes for him/her to feel secure. Do you already have a tank or anything? It would be helpful to know the details of your setup. Yes, you should have a UTH. It should ALWAYS be placed on the side, never the bottom, because Pacs burrow and will burn themselves if it is on the bottom. The UTH should be placed above the substrate level at one end of the enclosure. The enclosure should have a temperature gradient: a warm, drier side (with the heat pad) and a cooler, wetter side (with the water dish). With regards to the lights, you should get a lamp with a dimmer switch either way. It will allow you to tweek the amount of light so you can get the temps just right. Fluker's makes a 5.5 dome lamp with a dimmer switch.