75 degrees is the lowest it should be on the cold side, never less than that. The heat mat should be controlled using a thermostat. That temp should never really go past 92 degrees on the hot side, for belly heat. The temp gun will help you more than the stick on gauges would. I just got one and I love it. 50-60% humidity is okay for when not in shed. You should bump it up to 70-80% when in shed, which will help a lot. Keeping humidity is hard in a glass tank. That's why I switched over to a tub which is much more efficient for humidity. If you have anymore questions feel free to ask.
Cody