No don't use a dimmer switch buy this extra 30 bulb form my store... I think a dimmer is the best idea to regulate heat because when using a thermostat alone if it gets cold it turn on full blast till the temp get hot then shut back off. so it's full on or full off it doesn't hold the temp in one spot, it gets hot cold hot cold and the keeps an average temp but not to the degree and I know everyone loves their temp gun but unless it's a high dollar model the temp very wildly.
Not if it's a good quality proportional thermostat. Also, "high dollar" is relative (seriously - is ~$130 too much to spend to avoid burning your pet) - putting a price tag on the safety of your animals is something I don't recommend doing.