A few notes regarding the propane, I use a carbon monoxide detector as a safeguard and the model I linked to has a built in detector, if it's gets too high the flame is extinguished automatically. Since you mentioned your house is old and drafty it won't be a problem. If you run it at say 8,000 BTU setting a tank lasts 3 days, you can keep the tank outside and just run a line into the heater but I didn't bother, propane tanks are fairly robust, just make sure your connection is tight.