Umm...ok... I don't know who told you those pads wouldn't get really hot, but it's not true. 10g UTHs are 8 watts and they get upwards of 120 degrees if not controlled.

As for thermostats, heres the run down:
Low end: ZooMed ReptiTemp 500R. $20-30. Great for the low budget or while you're waiting to save up enough for a good model. Eventually should be replaced with a mid to high end, but can work for months with little trouble.

Mid-range: Johnson and Ranco. $70-80. The best stat for low cost. On/Off style (comes on when temp drops below set and goes off when temp goes above). Johnson is smaller and quieter, but otherwise no real difference.

High end: Herpstat. $110+. Proportional (always on, regulates the power to keep temps within tenth of degree). One of the best stats out there.
Helix. $130+. Also Proportional. Said to be best for large racks or incubators.

For a tank on top of furniture, yes you'll need some plywood below to protect the furniture as well as placing the rubber 'feet' on the bottom of the tank.