Roaming at night is normal. The most frequently recommended combo hygrometer/thermometer round these part is the Acurite indoor/outdoor (easy to find at your local Walmart). What sort of substrate are you using? Cypress mulch and moistened cocohusk tend to be better for increasing humidity. As for under-tank heaters, Ultratherm pads seem to receive better reviews than the ZooMed brand. People with PVC cages or racks use Flexwatt/THG Tape. However, this is less common for glass tanks. Is your UTH regulated by a thermostat?