Hard to say.Stick to fundamentals and remember rents rarely go down.

. ***** is not eligible for any type of refund but we will however refund him $*** for his dissatisfaction.

And prior to that it doesn't sound like you treated it as investment if 21.If you want to make this property eligible for a 1031 exchange you will need to establish your intent to hold it for investment use. 

You just need to talk to several lenders before you land on one that can use your previous tax returns and income to count towards your loan eligibility. 

The current term for hearing eligibility "Egregious Increase" is too vague.6.

With the properties Titled to a LLC, it isn't eligible for a conforming residential loan. 

Neighborhood Suburban (NS) Zoning - so newly eligible for a new ADU build.

The duplex is a business first, and in my opinion he should only live in one side for the minimum amount of time to make it eligible for the VA loan. 

I'm not a CPA and you should consult with one, but my understanding is that as long as you show profit from your SE activity - you will be able to contribute to a Solo 401k plan, the real estate losses would be on top of that (if you are eligible for them). 

Between these two, you'll have a solid fundamental understanding.