Once they discover that the hides are good and safe they're un-pryable. Most new snakes don't seem to know what the hides are for, or aren't sure about the safety, so they avoid them. Every new snake I've brought home has spent the first week or two curled up in the corner behind the hides. Heck, my new adult Het Albino female is curled up in the center of the tub with her chin resting on her branch(in the store, she was kept in a medium sized acrylic display box due to lack of room) since she's so used to open spaces. Her tub is covered, tho, to make her feel more secure.

As for a thermostat, if you're short on money I would suggest you order a ZooMed ReptiTemp 500R rather than spending your money on a maddening dimmer. Trust me, I fiddled with dimmers and rheostats for months at first before discovering that the ZooMed stats are just fine for short term use. They typically run about $20-30 and do a great job keeping temps once you get everything dialed in properly. Of course, you'll want to save up for the good stats (Johnson or Herpstat) ASAP, but the ReptiTemp will give you peace of mind about temps until you can get a better t-stat. The best site I know of for those stats is ReptileSupply.com.