If an individual earned a decent base income from a FT job (relative to the area), then doing owner occupant maybe 3 times in a row, for example, should not a problem...

There are 2 main tax reasons why you will want to use an S-corporation.1) Flipping houses either individually or through an LLC will generate self-employment income, which is subject to a 15.3% tax. 

@Michael Pursell following up on @Charlie MacPherson good comment you also may want to pay attention to the exact wording of this stuff and how its individually interpreted by the various building departments: Accessory Dwelling Unit, In-Law and other terms may mean something slightly different town by town and be treated differently, likewise if you owner occupy or not. 

The government assistance part is good on the payment, but bad in that they have no skin in the game.

I'll simply be assisting in the sale of the property?

As Chris mentioned, know the individual state laws.

I would not contact banks individually and instead let a broker tell you what you can qualify for and the best interest rates.

In FL, my wife and I turned our individual houses into rentals when we bought a house together that also had a carriage house so we had 3 rentals.

I was just presented with a VERY similar situation @Matt Tobler (grandma is going into assisted living, family is looking to sell -- 60,000 purchase est. value 100,000)I have the cash for the purchase, great credit and income for the subsequent refinance, a team in place to help with a fix and flip exit strategy and also a rental portfolio that is professionally managed for a hold strategy. 

Legal can come later, especially if you are purchasing multifamily as an individual.