Actually I wouldn't use a person for that listing, I'd use some agency because it's that regularized audience and having a known brand for tenants as "the" place to look that drives so much traffic. 

Don’t count on tenants to replace filters regularly.

Other than that, you'll have to check regular maintenance items (i.e. roof, heating and air conditioning, plumbing, flooring, etc).

The order didn't specify what the septic tank was filled with but the order from the Health dept stated it had to be filled with compactable material (gravel, stone or soil). 

If tenants were unable to pay I would be able to cover my payments on my houses with my regular job, I take home about 1k a week.

In your "vanilla" C-class value-add syndication pre-COVID investors were regularly shown an IRR of 15% over a 5-7 year hold period.

For example, for our first rental, we took a second "regular" mortgage on our house.

Regular 401Ks do not.

I have a deal on the line with an older gentleman (70) in poor health.

If you become an appraiser and all you're doing is determining values for regular sales transactions that won't add anything to help you with knowledge for a flipping business.