I have seen anything from roof only, to structure only, to both roof and structure, exterior mechanical systems, to parking lot, detention ponds and well systems, and even utility lines.NN especially in cold belt states can be a lot of hassle having to maintain certain aspects of the property for a tenant.Absolute NNN new build Dollar Generals typically range from 6.25 to 7.0 cap rates with 15 year primary term leases with flat rent until the option periods.

I understand that a 220V fuse would have to be installed in all the 39 panel boxes.

It's possible but rare. 50k at current interest rates don't make banks money, in fact most of the banks I know of who offer these types of mortgages have added additional flat costs below 60k to make it worth their time. 

If you know which end of a screwdriver to hold, you can probably diy it, no sweat.OK, you might need a flat tip screwdriver AND a phillips head.

Another possibility could be to purchase a home as a primary residence that has a granny flat or some type of ADU so you could live where you want and also take advantage of your VA loan.

We installed HVAC + ductwork instead of keeping the window unit, swapped the 120 amp panel for a 200 amp and changed the old cast iron and copper plumbing to PEX and PVC.New roof, floors, cabinets, appliances, light fixtures, paint, etc, etc, etc What made you interested in investing in this type of deal?

Mind you the roof is flat and have a total of 4 corner drainage spots. 

This is an 80-year old property with a flat roof, you'll be spending some money.Closing costs on a commercial property will probably be $5-7k.

He purchased a 2 flat apartment 50 years ago for $13,000. 

A bit of a blip during the financial crisis in very expensive areas (I watched it happen in Manhattan), but that quickly corrected itself as it had more to do with the over-heated market leading up to it.In most areas rents were flat or actually went up.