To address these issues, the lot needs to be properly sloped to divert water away from the building.

If you had to come out of pocket for a water heater for $1,000 in a given month, or a $300 plumbing call, or an AC call, can you comfortably do that type of thing with your finances?  

One thing that got me was the age of the water heaters.

They'd be way better, unfortunately society works the inverse therefore they'll always be under water.

Some areas and lots use well water others have city water.

My model projects these can be without private or individual site water, power, bathrooms, and/ or wifi and still be worthy investments. 

We’ve been tossing around the idea of converting one of our bedrooms into a gym (treadmill, weights, bench, etc with towel and water service).

You aren't "dead in the water" by any means.However, there's a piece here we don't know - how much do you owe on the property?  

In spite of all that work we discovered that the hot water heater didn't work (they didn't bother to replace a $300 water heater that their initial 4 point inspection stated was original to the house (1983).  

I Expect not, I expect the water to get to my property even more in the next few years.