In the order I would consider: (After I insulated at least a little)
1 - Electric is safe, and very cheap to install. You could probably pick up a few baseboard units and the local Habitat store or on Craig's List for very little $$.
2 - An additional zone on the oil - why duplicate what is already there? (this is only #2 because of cost)
3 - Gas - a viable alternative. Can be expensive to install and you need to be very careful if you use solvent based finished - especially if you spray.
4 - Propane - ugh. stinks.
“We all die. The goal isn't to live forever; the goal is to create something that will.” - Chuck Palahniuk