you should really take the ground temp on the hot side with a digital probe thermometer or temp gun. those UTH's can heat up like crazy if you dont' have a thermostat on them. the ground temp on the hot side (under his hide) should be 90-93. the ambient in such a big glass tank is probably going to be slightly lower than this range. the ambient temp on teh cool side should hang right around 80-82. To help keep this up, you could try insulating three sides of the tank with that 3/4" pink/blue insulation board. You'd be surprised how much heat is lost through the glass.

As for "professional" setups, I would suggest a Helix or a Herpstat thermostat if you are going to invest in one. they seem to be the favorites around here. I use the helix and i love it. For keeping the humidity up, try covering 50-75% of the top with tinfoil and duct taping it down. I had luck with that when i had mine in tank setups. just make sure the snake cannot come into contact with any sticky parts of the tape.

I wouldn't worry if you don't see your snake drinking, he may be doing it at night when you are sleeping. I haven't heard of anyone injecting prey with water. As long as you provide a clean, fresh water for your snake, and keep humidity in the 50-60% range, you shouldn't have to worry about hydration.