For the temperature problem You could possible try moving the heat source a little closer to the cool side, so these is less of a temp gradient. Another option which may not be an option for most people is to increase the room temperature. A third option would be to get an undertank heating pad and thermostat for the cool side.

FOR THE HUMIDITY PROBLEMS
When i had tanks I had the same problem, and found a few ways to get humidity into the 50's.

try increasing the size of your water bowl, this may help some.

what really worked for me was covering most of the top of the cage with a wet towel/cloth. I covered 2/3 the top with a t-shirt. On top of that i had a small towel that I would soak every day and put on top of the t-shirt. This way kept the towel damp for about 2 days. When you feel the towel getting dry, take it to the sink, run it under water, ring it out just a little, and put it back. this method works, but requires you to re-wet the towel every few days.

I am no expert and you may get better suggestions from others, but I hope these help. Most of all dont kill yourself worrying about these things, there are ways to fix this and you will figure them out. Getting too stressed doesnt help anyone and in fact gets in the way of clear thinking.
GOOD LUCK