Then, I asked him, what my chances of applying for an FHA after would be. 

The best advice is to try not to sell with a SCBN, but if you must to get the deal done, then the above would apply and takes extra planning. 

He suggested setting up the house with an Accessory Dwelling Unit (ADU) and applying for a conditional use permit.

Keep in mind, with an LLC you will be applying for commercial financing when you purchase rental property.

Or, hire a quality PM company and then have your ex-wife's husband apply for a job with them.

The primary residence exemption would only apply to the unit you occupied.

Generation skipped tax will not apply as the amount of the inheritance ( estate)  will NOT exceed 11 mln.The property guardian will be responsible to pay real estate taxes, house insurance, etc. from the rent. 

Same applies to 4 bedroom homes.

Also although i’m aware of “flat-fee”, and “split” brokerages, but I’m on the fence of which to apply to in each state once I get my license.

I've only applied for them one at a time.