Hello.

I personally use newspaper as a substrate, but with eco-earth I would think 1/2 thick is fine. You don't want it so thick that the heat from the under tank pad can't come through. It doesn't really matter if it's packed down or loose.. your snake will mix it up when it crawls around anyway.

You will need a digital thermometer to measure your temps.. preferably 2 (or an indoor outdoor thermometer that can take two readings, one for the warm side and one for the cool side) temps should be 80-82 warm side and 90-92 on the cool side. You should also have a digital hygrometer (to measure humidity which should be between 50-60%)

You said the bulb is on a thermostat, but is the under tank heater? UTHs get quite hot and can burn a snake if they are not on a thermostat.. I'm not sure I trust the repti temp thermostats. I use Johnson and Ranco on/off t-stats.. though the best are the proportional t-stats (Helix and Herpstat)

You should have at least two hiding spots for your snake, one on the cool side and one on the warm side. It's fine to place it directly above your heating pad.