You should try the thermostat yourself, it is really easy. kinda plug and play with your old mercury one, KINDA. You might need a drill to mount it and a screwdriver. the other stuff is easy if you have existing electric lines there and you are just replacing stuff, it's recommended to have a brace in the rafters for a fan. for an entirely new instal in which they have to run new wire and connect to a breaker box contact an electrician. I had a pretty good one instal a new main line and breaker box and also some new line when I bought this house, if you need I can find their info.
edit, looing at what you need done, it is basically homeowner stuff, I wouldn't worry about using a licensed person, unless you need new wiring connected to the box.
Sherm's the man with trustworthy construction advice, I suggest contacting him if you have major concerns.