The condo has some issues: a faulty breaker box, old and not well-sealed windows, and uneven floors.

You may have some extra costs, like dumpster versus city trash collection or parking lot sealing and striping from time to time, and possibly different building standards if you are doing major renovations, but day in and day out they are very similar.  

and deal with power lines, water lines and sewer, maybe seal the well. 

So, the pond sealed well. 

@Michael BertschAs a general rule, we only leave a fireplace functional unless it has a sealed, externally vented, gas insert ... and, even then we may disconnect it.Check with your insurance provider and see how unhappy a functional fireplace in a rental makes them.

If you get front loading units tell each tenant not to overload the washer because it will cause the seal to give and make the unit leak.

It is usually much easier to seal a existing door way then it is to move walls in my experience. 

You're like the boat builder who doesn't know to seal the planks.

To avoid the risk management/insurance that comes with tenants' wood fire use:I'm thinking to seal the chimney cap on roof and run a cord putting an electric Infrared heater fireplace in there, so they can still open the glass and get heat and watch TV over the mantle, but can't burn anything or have any flame.

Will put grey epoxy with "colored sprinkles" on the surface to help seal the concrete.