You want to keep the depth of the substrate low because you are using a form of belly heat and the heat needs to find a way to get through the substrate. Please remember to monitor the hot and cool side temps on the glass under the substrate!! Very important!!
Argentra will need to address closing the lids, but I seem to recall others using those office supply clips...?
Oh yeah, the hides: keep one on the cool side and one on the warm side.
Lastly, remember that it takes over a week to get the tank stabilized once you have everything hooked up.
Ooops, you never mention a THERMOSTAT. Do you have one?? You need one.