No need to feed in a seperate container... You will actually lower your chances of him eating, and increase your chences of getting big by moving him to a seperate container for feeding. A BP will never mistake you for a rat unless you smell, look, and are the same temperature as a rat (100 f)
A thermostat isn't optional. Heat mats can easily get to 150 degrees. That is hot enough to kill your snake. It may not feel that hot yet, but it will get there eventually.
A thermostat uses a temperature probe to adjust the power going to the heat mat. It does everything by itself.
Don't bother with the thermostats sold in pet stores, they are all a waste of your money.
Here are 2 good thermostats:
1. The hydrofarm thermostat, sold on Amazon for $30 these are the bare basics thermostat, considered to be the cheapest "acceptable" thermostat on the market. These will do their job, but lack the accuracy and safety features of better thermostats.
http://www.amazon.com/gp/aw/d/B000NZZG3S
2. The Herpstat is the best of the best. These thermostats are extremely accurate and have multiple safety features built in. They have a higher price tag though. The entry level model runs $99. They are worth the cost, and make it much easier to provide the proper temperatures
http://spyderrobotics.com/
Do you have a probed thermometer? If nit then you have no way of telling how hot the heat pad really is. Heating pads don't change the air temperature in the cage. All they do is increase the temperature of the floor of the cage. This means that if the room the cage is in ever gets below 75 degrees you will need another hear source to keep the air temperatures above 75 (78-82 is ideal)
This is a good thermometer. It costs $12 at Walmart and measures 2 temperatures (hot side and cool side) as well as humidity.
Finally how thick and what are you using for substrate? When using heating pads your really need the substrate layer to be 1/2" thick or less for the heating pad to be truly effective.