In terms of mitigating your risk - particularly if you buy a condo - consider a newer building, steel or masonry construction, a unit on Floor 3 or above where Flood insurance wouldn't be necessary, larger buildings where costs are spread amongst more owners, and buildings with a financially healthy HOA (track record of good management, reserves in the budget to cover large capital expenditures, etc).

The renovations included new flooring, fresh paint, a new HVAC system, updated bathrooms, and the addition of stainless steel appliances and granite countertops.

Working on The contractor and The lender slots right now!

I have also heard that its better to have black or white appliances for long term rentals as they don’t show dents as much as stainless steel does, but the stainless-steel look is the look that surrounding rentals are going for.

@Clint JusinoAre all the drain lines cast iron and the supply lines steel?

Steel screw outlets are probably the main problem area, but anywhere connections are made can cause problems.

Drill a hole directly above the slot for the key and you destroy the locks integrity. 

Unfortunatley there is no easy solution, this basement is just past its useful life.The only real solution here is to suspend the house on steel beams and then remove the basement from underneeth.

There are cathodic protections on the steel gas mains, and if there is an issue in your meter that could be somehow causing the issue.

Additionally, the structure for these porches is commonly undersized and may need repair work including but not limited to sistering joists and providing steel angle brackets at the notched beam to column connections.