As one person already mentioned, covering the top of the screen tank with foil helps, I do this for my humidity. However, I don't mist the cage (I don't want the substrate damp all the time), I put warm damp towels under the foil, this keeps my humidity between 50 and 60%, I just have to re-dampen it about every 24 hours. I also replace the towel every few days so it doesn't mildew.

Petsmart most likely was underfeeding him. So as soon as he is nice a settled in (a week or so from when you got him), get an accurate weight so you can get the correct size prey.

I hold / handle mine boy every day (except for the two days following feeding and when he is in shed). Sometimes he's out for 20-30 min, other nights I just pick him up long enough to give him a quick look-over while I'm changing his water and checking his hide for mess.

Mine only poo's every 7-14 days, but went 20 without defecating when I first got him. There does not seem to be a pattern. The longer he goes between the larger the mess is when he does go. Believe me, you can smell it. He does urinate every few days. This does not smell, but I will find a little white chalky pile (normal urates) in one of his hides. Then I spot clean that area, and replace the wet bedding. I usually know when he's done this because he suddenly stops using that hide and will curl up in a different one, or beside it.

If you haven't already, cover three of the sides of the tank with dark paper, this will make him/her feel more secure. I don't use an under the tank heater (UTH), I use ceramic heat bulbs (CHE), but what ever heat source you use needs to be regulated. Both the UTH and CHE's can get extremely hot and either burn your snake or make the hot spot intolerable, which could force him to the cool side all the time.

Other than that, he/she is a nice looking snake and you'll have a ton of fun with your new little scale-pup