I have a detached back room 231 sq ft that i am currently using for storage has only electricity going to it, 2 ceiling fans, 2 windows, no plumbing, gas, or air conditioning.

If power goes out, they need to have candles, blankets, coats, or be prepared to go to a hotel at their expense (or they can sue the electric/gas company).

PM and Realtor seem confused on the vacancy as well.Since both the 2/1 and 1/1 share a meter, I pay for water, trash and gas.

Peninsula includes slide in gas range and seating on other side.  

In this case we started with charcoal to heat it up. . .then got a clue that was a dumb idea due to probable proximity to the gas line and switched to a space heater.

typically though Fee simple ownership of the land includes all the tree's  trees are real property.if the mineral or gas or oil rights are not reserved then the fee simple owner owns those.. someone leasing the land has no rights to any of these. unless there is a contract that specifically spells it out.thats why you have mineral rights in deed form.. you have Timber rights in Deed form and Water rights especially on the west coast were water is a major issue as well think the old western movies.. 

I would need to put in $25k-$40k of rehab into the place (ac, roof, gas, and much more).

This includes water, gas, electricity, cable, and internet. 

Once I got a new gas boiler and managed the thermostats, the cost has been very manageable.

Carbon detector if there are gas appliances in the building.Your area might be different but this is the standard requirement.Good Luck.