If you are buying site unseen make sure to extensively use google maps and get a good idea of what the neighborhood looks like.

IF you like his site, you can stay for $59/month or so....but to be honest, most anything you can learn on his monthly updates, you probably get 10 times the education here on BP for free.

Most people like to see who they are communicating with on this site.  

are there any sites where I can directly search a list of qualified tenants?

I accept Direct Bookings by the way, and some are sourced from sites like Furnished Finder. 

I could pay a regular marketing firm to build a site, but since so many STR owners have this need, I have to imagine there's an off the shelf option rather than having a custom site built.

The online realtor sites give you dates but they are usually in the past and always have a disclaimer that " Auction time and dates can change".

But agree third party real estate web sites don't update status changes of a property based on my experience. 

You’re on-site for maintenance issues or tenant concerns, which cuts down on the hassle of traveling to a separate location.Loan Accessibility: Getting a mortgage for a duplex can be easier than financing other types of investment properties because you can use the potential rental income from the second unit to help qualify for the loan.Tax Benefits: Owning a rental property can open up opportunities for various deductions like mortgage interest, property taxes, operating expenses, and depreciation.Disadvantages of Investing in DuplexesPrivacy Issues: Living so close to your tenants means less privacy.

E.g. location, site constraints, your general questionsTo your question, I'd also be happy to hop in with recommendations.