From what I have heard, humidity is a bad thing. It can lead to respiratory issues. I think a fogger would be a bad idea. All they really need is a bath for 15 - 20 minutes a couple times a week, depending on age. You can also give them drinks of water from a small syringe by dropping small drops on the end of their nose.
I don't have a number for you, it would depend on what your tank was made of, ventilation and temperature from heat bulbs but I can tell you 100% that it is not suitable for a bearded dragon. They look really cool but like Nibbles made they are for tropical species, defiantly not beardies.