Here are some things that I want to do, but I want to get your opinion and any other ideas- charge a flat rate for each unit each month, and obviously this would be written in the lease and tenants would know ahead of time- charge a rate by sqft, so tenants occupying 750 sqft pays less than 1000 sqft unit, rate is FIXED and known at signing- charge a rate by sqft, so tenants occupying 750 sqft pays less than 1000 sqft unit, rate is VARIABLE and is calculated from actual water bill- increase rent price?

It seems like a great idea to get a HELOC on your property ( if it has equity) while its still owner occupied, you will have funds available when you find your next deal.

Or is it better to hit a neighborhood you like and just filter for equity and owner occupied in PropStream?

If you are not occupying the home during the application process is will be considered a rental/NOO - Non owner occupied home. 

If you are going to owner occupy a duplex, you should go the FHA route since the downpayment will be so much less. 

Condos usually have hard owner-occupied percentages they have to meet and you might not have that opportunity, unless the condo is specifically an investor complex.  

@Hilary Harrison Charleston county charges 4% on owner occupied primary residences (your house) and 6% on any non owner occupied structures or second homes. 

If 30% of SFRs are investor does that mean 70% are owner occupied? 

We will be looking to purchase a 4 family home and my partner will occupy one of the units.

I'd rather the place sit empty for a month while I find the perfect tenant than sitting occupied for several while I fight out an eviction.