Morning Emily!
You've asked some excellent questions here, I'll try my best to answer them for you. First off, I will commend you for doing your research before getting a chameleon, they are not an easy animal to care for. They require a lot of detailed work on a daily basis.
I'm assuming you are interested in a Veiled Chameleon. That is species that Mary just acquired. Click
here for a good care sheet on them. If you are interested in a different species, let me know and I can direct you to other ones.
1: Handelling: I always say not to handle your chameleon. Most chameleons don't like to be held, they hiss, they puff up, they bite, handelling just causes them great stress. Marisa is right though, there are some individual chameleons that don't mind it at all.
2: Housing: I don't really recommend a tank for a chameleon, but I've used them to house babies temporarily. I use a 24x12x18 size tank for mine. (is that a 15 gallon?) I will use this until they are about 3 months of age then they get transferred to an all screen enclosure. Please don't wait until it is an adult to make that enclosure!
3: Lighting: UV is terribly important for a baby chameleon! No access to UV; no bone, tissue, organ growth! They use the vitamin D in sunlight and change it to calcium to make those body parts. I use the Iguana Light 5.0 on all of my cages.
4: Veiled's need 50-70% humidity daily. I mist all of my chameleon enclosures twice daily for about 10 minutes each with regular tap water. Humidity is important to chameleons, but it's during these misting periods that chameleons will drink. Dehydration, not lack of humidity is the biggest killer of chameleons!
Hope this helps in some way!
Trace