red headed agamas

Question
Sunday, I got a red-headed agama froma reptile convention. I noticed right away that something was wrong with him. He was not eating anyhting. He was not very active at all. When I put him in his cage, he sat there and closed his eyes. There were crickets jumping all over him and he didn't take any notice. One sat right on his head, and he did nothing at all. At first I just thought he just needed to get used to his environment, but when I went in there Tuesday to check on him, he was dead. I then noticed for the first time how skinny he was, and after 3 days that he hadn't eaten or drinken anything. Do you have any idea on what may have caused that? Trauma from traveling? A parasite?
Another thing, I want to get another agama,but I have a few questions first:
Are red headed agamas prone to any serious health problems?
Should I get it checked by a vet when I first get it?
What's the best thing to use for cage flooring?
What is the normal activity level for these lizards?
What is there normal behavior like?
Any vivarium set up advice? (I have a 20-gallon tank with a rock, a basking area, a water dish, and UVB and Heat lamps)
Thank you so much

Answer
Long story short: red-headed agamas are what the industry calls "junk lizards."  Now, before you get angry, here's the story.  Importers are kind of at the mercy of the exporters from which they want animals.  In order for US importers to get ball pythons from Africa they must also buy some "junk."  Red-headed agamas cost me about $3-7 each, I sell them for $10 and inform everyone you buys them that they usually need to be wormed, many of them will die, and we have no way of knowing if they are 5 months old or 5 years old.  Hence, when you buy one, you are taking a big chance.  

Because they are so cheap there is not a ton of info out there as to care.

Here's what I've been told:

Insectivorious
Sand as the substrate
Very active when up to temp, healthy, and food is introduced
Normal behavior would be seen as a flighty lizard (tries to get away)
Sceen cage would better than glass and probably 40 gallons minimum for one.
Your lighting is correct assuming your basking spot is around 100F
Vet check is always a good idea w/ imported lizards BUT that vet visit will cost you more than 2-3 replacement lizards so...  
I don't recommend handling them at all until they are feeding well and gaining weight.

I did once sell one to a student of mine, he followed the above advice and his lived for several years-never really calmed down though.

Unless you like a challenge or have a lot of experience with lizards, bearded dragons and leopard geckos are MUCH easier to deal with and all are captive born.