It would be painful to have to revisit this in 15 years and try to argue your case.

If your answer is that I should just give them notice, then do you also have any strategies you use in cases like this to help minimize the pain?

You can't use your VA loan, the terms are worse (which is painful as a beginner), finding financing is harder, and getting sued is a statistical unicorn.

It is still a bit painful for me to even type this out.

The assessed values for tax purposes on all my properties are higher than their actual values.The county assessment is usually quite accurate and to be painfully honest if your is on the money you are lucky as assessments are usually on average higher than comps.You would wasting your time challenging what you already know is right.

It'll be a pain in your ***, but doable.

The rehab can take 2 weeks, 2 months or 2 years and be quite painful educate yourself avoid costly mistakes. 

They can be a pain in the butt with lots of fees.  

What I can think of the rest of the work for the house is: Sheetrock, paining, flooring, installing cabinets/counter tops in kitchen and bathrooms, tile up around showers, appliances (water heater, dishwasher, range oven, microwave oven), light fixtures, interior doors.I am posting here to seeking advise on any major to-do items I missed?

He's got the property and the financing 100% in your name, like a good flipper you are in and now out of ownership in that property with hopefully a tidy profit, him and his wife live happily ever after, everyone gets what they want.I have no idea what parent to child transfer rules are in PA, in CA (and specifically the Bay Area with our crazy transfer taxes) this would almost certainly be the way to go in order to dodge both transfer taxes and a property tax reassessment.