I'm not sure why not - one of the great parts about real estate investing is that you can build a team around you for aspects you aren't as strong at or simply want to delegate to someone/expert and do the others yourself - look up "Core 4" for example - where you can have an agent, lender, manager, contractor all at once for your investments and can theoretically just let them do all the interactive work

For the HVAC, I'd just question if that's the correct and best way to go about it, but I'm not an expert, but certianly you won't get interest listing a unit for rent or sale without HVAC.

Remember, the notion of amassing wealth without investing is a dangerous myth perpetuated by self-proclaimed experts.

Go through your goals and make sure what they know and are an expert in lines up with exactly what you want.

From that experience, I got the idea of just building a multifamily (ideally a quadruplex) from the ground up as my next home to house hack in.I've done some preliminary research and had some questions if any experts care to chime in:+ There aren't many multifamily zoned lots in metro Atlanta.

Be an area expert on contracts, zoning, value add components, contractors, and so much more. 

Remember, the notion of amassing wealth without investing is a dangerous myth perpetuated by self-proclaimed experts.

Just curious why a certified letter would help? 

You must give him this letter in writing, or certified mail, or tape the letter on his door.  2.

Basically, you're saying your intent is not to move in, but with owner-occupant loans for lower downpayments, you will sign a statement certifying your intent is to occupy the property.