I had needed to replace the furnace and some electrical, and updated the bathrooms before renting it.

Also depends on how expensive it is get the electric to where you need it for the outside compressor.  

I agree with @Rhett Tullis and @Arlan PotterWater should be no different than gas and electric. 

Once we started construction, we ran into several major problems including a steam pipe running through a kitchen wall that we were planning to open up, a huge leak inside a couple of walls that required the replacing of a whole exterior wall, damaged subfloors, major termite damage that resulted in a replacement of the sill plate in the master bedroom, needing to upgrade full electrical service (and split it into two separate panels) and a corroded water line that required emergency replacement all the way to the street in the middle of winter during record setting cold temps and a snow storm.

Technically if you have a decent sized upstairs you can turn your basement into one with a small amount of plumbing and electrical work.  

They cover major issues with plumbing and electrical too.Cons: Cost to cover major things in your household is about $635 per year.

I'll start off by saying believe in the power of CL (craigslist) I don't let a day pass   without utilizing that site.my advice to you would be log on CL search area's within a 2hr distance from you go under real estate fsbo filter your search with we buy house's or I buy ugly house's and investor special,once you find these ads start making phone calls,reason being these investors know their local market and have their hands on the pulse of that farm area.After dissecting all the useful info from local rei,I generally go to google streetview and walk the neighborhoods to have a better understanding of there market.Trust me it works I just closed 3 wholesale deals in Birmingham,Al using those same techniques,I was fortunate enough to find a we buy house's sign on a street corner zoomed in on the sign called the number and almost 2 months later the deal was funded.I hope this post serves you willCheers!

No plumbing, electrical, windows, fixtures or mechanicals.

Now that your under contract you definitely have a little more power, especially with it being on market for so long.

First was HVAC, then plumbing and electric--I do not leave those items to a handyman.