@Tyler Speelman There's no issue if you want to convert your STR into your primary residence and live in it for those two years. you would qualify for a 121 exclusion which allows you to take the first $250k ($500k If married) of the gain tax free. 

I will only mention two critical points:- People with regular full-time W2 jobs cannot qualify for REPS (unless their no-W2 spouses can qualify)- REPS has nothing to do with STRs, and vice versa3.

If you're doing a 2nd mortgage on your primary residence to get the cash for down payment on the new Quad, then you're looking at needing to qualify with DTI unless you find a lender who is a DSCR lender and not a traditional conventional loan lender.  

Since you are an active service member the IRS will allow you to have lived in the property for two out of the previous ten years of owning it. you'd just want to verify with your accountant that you qualify for these extensions.Since you converted the property to investment, you may also take advantage of doing a 1031 exchange when you sell.

I been watching some videos where the get a 5% down with FHA loan but I don't think I would qualify.

This might be a dumb question but would it be possible to use my significant other as my "roommate" to qualify for a house hack?

There are multiple ways to qualify for "material participation" but this would help to keep someone else under 100 hours. 

After that it’s best to transfer the property to an Ohio tax deduction qualifying entity.

Legally, the GPs take on the liability of the project including things like signing on and qualifying for loans.

Do you mean you go to the bank then they qualify you for the loan and approve the transfer?