When you offer yourself as a lender, there will be all sorts of people that will come up to you, but ideally you would get to know the person that you are lending to.

I am a small fish in my local pond yet I am approached weekly, often daily, via calls, texts, and emails from people who "live in an expensive market and have identified ______ as an ideal Long Distance investment location and will be buying ____(insert audacious number of homes here_____ in the next year." 

it's not ideal and a pretty ****** situation. with that said it was my very first property,  I sucked it up  and did what I had too.   

If the rental real estate activity has an average period of customer use of 7 days or less, or an average period of customer use of 30 days or less with substantial hotel like services provided, it is not a rental real estate activity under IRC Sec 469 and one can bypass the per se presumption and apply any of the material participation tests you previously cited for a passive/nonpassive determination.

There is not really any assessment of the quality of work or customer service, nor is there a reason to use them based on fair and reasonable pricing.

Save the custom build until you're older and have lived in a few places.Look for a MFR (I think 3- or 4-unit properties are way better than duplexes), live there a few years, and then turn it into a pure investment property.

Well you need a source of deals, and a sheriff’s auction could work, I’ve seen a number of my customers be successful at that in NC.

And that may be a big assumption depending on the type of work the S Corp does and where your customers/clients are located. 

Guests are my homeowners’ customers.

It may pay to keep them with one financial institution, as some banks provide lower interest rates on loans or reduce fees for customers with multiple accounts.