The best place to start is with a spreadsheet that has every every cost itemized. 

I am bullish on the FHA 203k and home-style renovation loans that allow you to leverage the cost of your renovation as part of your mortgage, which is just an insane deal, in my opinion.Do you have a specific area where you want to purchase?

I would tell people today that if you buy a primary residence expect to stay in that home for atleast five years, especially with a FHA loan which has lower down payment as the current forecasts for home appreciation or very low which with closing costs on the buy and sell, it will take several years to have equity in the property and enough to be able to sell, so that is something also to consider.

OR potentially a lease to own option.

Namely, that if a tenant (in this case accompanied by a whole family) ends up stop paying rent and I would be on the hook for both covering the mortgage and dealing with open ended legal costs and time.

Definitely a strong location with great visibility and high foot traffic.Since it’s a NNN,  your expenses are minimal, but if LazyDog ever exits, buildout costs will depend on lease terms and the next tenant.

My main question is whether it makes more sense to go the seller financing route and pay off the principal in 8–10 years or stick with a standard 30-year loan.My thinking is that the tax deductions from a mortgage wouldn’t outweigh the potential equity I could gain over those 8–10 years.

Can try to reposition to Class B, but neighborhood may impede these efforts.Vacancy Est: Historically 10%, but 15-20% should be used to also cover tenant nonpayment, eviction costs & damages.Tenant Pool: majority will have FICO scores of 560-620 (approaching 22% probability of default), many blemishes, but should have no evictions in last 2 years.

But, these broad market studies are so large, they are almost meaningless, in the real world.Between glut of new supply in many "hot" markets coming online, a continually softening economic outlook, inflation over last couple years making day to day items feel cost prohibitive, many average renters are strapped and seeking lower cost housing.  

We have 2 San Antonio sub2 deals that are turn key homes and only require about $20-25k to close (assignment fee + closing costs).They're a great option!