Hi Tanya and welcome!

We have her in a 20L tank with repti-bark as a substrate. Right now she only has one large hide on the side with the UTH. The large water bowl is located in the middle and a tree limb on the other side. The lights (when in use) sit atop the locking screen top above the hide. She is about 1 1/2' long and I'm guessing (from the pics I've seen here) she is a 'normal' bp. She HAD some greenery in her cage until a little mishap the other day which I'll explain in a moment.
You want to offer him/her two small, snug hides if you can. Even something as simple as small plastic cereal bowls from Dollar Tree with entrances soldered out of them work very well. They choose security over thermoregulating, so ideally you want identical hides on each side, so that they don't have a favorite hide that they'll stay in rather than moving back and forth.

Is a light source necessary? We were told to have a light (heat source) on for 12 hours and off for 12 hours. We have both a white light and a red light, both of which are 60w if I'm not mistaken. Only one is used at a time. If it is necessary, does it matter if we use the red or white bulb?
No, light is not necessary, unless you need it for supplemental heat. Light is challenging, because it tends to take all the humidity out of the air, while you're trying to maintain a consistent 50% humidity. If you need to use one, I'd choose red over white, because white is just like a snake having a spotlight on them, and being nocturnal shy creatures, that can be a bit disconcerting.

UTH - We were told to adhere the UTH to the bottom of the tank and that adhesive strips would be included....but they were not. According to the caresheet I found on this site, this bit of info is wrong. What is the proper thing to do?
Be sure that this UTH wasn't peeled from another enclosure before being given to you as the process of removing the standard pet store UTH's can damage the wires inside, creating hot spots.

You can use aluminum plumber's tape (you can find it at home depot in the plumbing section) to attach your UTH to the bottom of the enclosure. Are you using a thermostat or dimmer to control the UTH? UTH's can reach levels that will burn the snake if they aren't controlled.

You also should pick up a good digital thermometer/hygrometer. The one that I use comes from Walmart in the hardware department for about $12. Takes a AAA battery. And I attach mine inside the enclosure on the cool side with velcro (so the snake isn't always knocking it over) and run the probe to lay inside the warm side hide on the surface. This is what it looks like:



Feeding - She was being fed small mice once every two weeks but the majority of the people we spoke with suggested to feed her fuzzies (?) once a week. Does this sound right for her size? Also, would you suggest feeding her in her enclosure or in a seperate enclosure? Keep in mind, my 13 yo son will be handling her. We do have an extra 10 gal tank available.
I feed in the enclosure with all of mine and I do not have any problems handling any of them. They know what day is feeding day and I'm in their enclosures almost daily, so they don't make any association with my being in the enclosure with feeding. I also make sure that if I've handled any rodents, that my hands are washed and the scent of rodent isn't on me when I work with the snakes.

Even hatchling ball pythons can feed on hopper mice for their first meals, so unless you're talking about an older fuzzy rat, a fuzzy mouse is much too small.

I feed babies about every five days and juvies to adults once every seven days. A small mouse once a week for now should be plenty.

She is pretty darn active compared to the other balls that we've seen. When we had the greenery in her tank, she would totally re-arrange it by morning. Since taking it out, she hangs out on the tree limb and climbs and explores everything!! Is this normal? Do you think that maybe she is not comfortable in her surroundings, still hungry or what? Any suggestions?
She could be a little stressed, a glass tank doesn't offer a lot of security for them, and the hide is likely much too large for her right now. One option would be to set her up in the smaller 10 gallon for now and use small snug hides, the other is to really clutter up the larger enclosure. Two snug hides and although not pretty - fill up the enclosure with loosely crumpled newspaper to give her more cover and help her to settle. You can start weaning her off the newspaper a piece or two every few days.

My son is away visiting his cousins so she has not been handled the past few days and not since this has happened. I'm afraid of how she might react when he gets her out the next time. Any suggestions?
Most ball pythons are pretty laid back animals, so she should be fine. He just needs to keep handling sessions brief and positive as they get to know each other.

I think in time, because you care so much that she gets the best possible care, that she's going to really grow on you. We've had so many member join here that were terrified of snakes, until they got their first ball python, and now adore them. We have another mom here who's daughter went to college and left her snake with Mom to care for, who's been working through her fear of the snake to work up to her first handling, and now feels that she's really going to miss this snake when her daughter has a place where she can keep her, herself.

Some excellent books - I'd start with Kevin McCurley's The Complete Ball Python (click the title to go to where to order it) would be perfect for you starting out. After that, and you are hungry for me, you can pick up Dave and Tracy Barker's Pythons of the World, Vol II: Ball Pythons

And if Kevin's book is more than you anticipated spending, he does have a more condensed version called: Ball Pythons in Captivity