How hot do your ambient temps get? I wouldn't feel comfortable having a crested gecko if my temps were going to be above the low to mid 80s on a regular basis. I've never had any personal experience with high temps, but from everything I've read that's a big NO NO.

I'm not sure how to cool just one room or area down. Maybe if you make another post in the general herp section more people will see the question and be able to pitch in.

I have had bad luck, no females for me yet. I don't see a reason a male would need a lay box but my male loves his moist hide. For unsexed hatchlings, a ton of fake foliage and paper towel tubes work great to give them places to hide and feel secure.