Bonus is I am getting new HVAC, Furnace and hot water tank. 

Improve the grade if water flows toward or pools near the house.

Labor/material are going to be different and need to factor that in4) new roof, new HVAC, new water heater, ac panel, replacing plumbing to PVCThese are very variable, if you are getting this from a licensed guy to do it and unlicensed.. is it a big shop or a local shop doing it, is the GC doing it they will put some money on the top so it will be more money5) framing (creating new bedrooms or baths)I would get all these quoted from a good couple of licensed guys and unlicensed to know your numbers to cents

By improvements I mean that there is power, water and sewer/septic installed and working.

It also has the benefit of being local which is great training wheels as you learn how to be a killer host.Now assuming that you mostly want a cool property to stay in sometimes near water and don't want to spend a ton of time managing I really like the outer banks in NC.

You mentioned that you've been paying water / sewer for all 4 units. 

No extra fees added for repairs, I'm allowed to contract my own people via the PM to do services(HVAC, lawn, water heater, etc.)

You can lead a horse to water but you can't make the horse learn math.

ON the more risk type product we do land speculation and Land entitlements but the returns blow most any cash flow at the the same dollar amount out of the water..

I generally agree that buying SFH as first investment is an easy way to test the waters; however, if you’re set on REI I suggest buying a duplex or quad.