We are undecided on whether to put down asphalt or gravel to help increase value to our home & property.  

Make it attractive enough and someone might be willing to partner with you.

So, whatever that requires.Learn how to attract and partner with private lenders.

But they also COULD show that the ratio starts decreasing (or increasing) with larger square footage.

Also - on condos or townhomes, an increase in the monthly HOA fees or a special assessment might wipe out your return.I caution you against counting on appreciation.  

The BRRRR method is quite attractive to me, I'd like to buy and hold and get great value in that. 

Of course you'd be inheriting any unknown liabilities of the LLC, and you'd be assuming the llc's basis in the property and depending on the LLC original purchase price and depreciation taken, a much lower basis than your actual "purchase price", increasing your taxes when you sell.

The long-term tenants are in a 1-year lease that is actually $200 per month below current rental rates - the current owner has not kept up with the rental market, and has not properly raised rent as the demand has increased.

You will be looking at recognizing the increase now as opposed to later.

If they do not fall within the guidelines for a warrantable condo, you can still obtain financing under a non-warrantable program but the rates & terms are not nearly as attractive as the conventional financing.