It will be a lot cheaper to install, though it is the most expensive way to heat a home, short of burning $100 bills in the fireplace.I have electric baseboard in the home I just purchased, so to mitigate the costs, we purchased (not leased) solar panels. 

It sounds like a challenging commercial property that will burn a lot of cash.

But like you said there are so many unknowns  and the risk  of burning through 5K for things unseen is highly likely.I think 20k is a decent buffer for the unknowns and the possibility of the sale not napping ad quickly ad o would have hoped for. 

Frankly if someone had threatened me personally I would have called police, I would have sat in my car until officer came and took report, I had tenant threaten he'd burn the place down..

Every time we renewed our lease it really burned my posterior so I read the book straight through and got in touch with Ben via email.

So familiarize yourself with the different ways payment can be processed, because many landlords were burned...https://www.biggerpockets.com/forums/52/topics/500...

Some people just posted stuff for the Superbowl then forgot about the listings.Read some posts from @Al Williamson he is helping a lot of people get their airbnb's going and currently pushing a 30 day minimum model as a way to get a premium over long term unfurnished but not burn out from too much turnover

Just don't want to get burned. 

-Oil burning furnace: Fire hazard with amount of buildup in furnace and in flue.

Usually the folks who get burned are the ones who fail to ask themselves "what can go wrong in bad times, and what have I done to mitigate that risk" (e.g., you flip a house with HML because you think the market is hot and ARVs in 3 months will be at current or higher levels, but don't plan for a market slowdown).