While you are not required to have a property manager for your long-term rental (short term is a different story), you can only handle administrative functions such as making phone calls, paying bills, selecting a contractor, etc. and must be completely hands off. 

I am interested in recommendations for online courses or books (or other sources of information) that people have found useful. 

I would need more information to truly answer these questions as there are some nuances here that require further discussion.

There are documents that normally third parties will ask you about your 'status'If you work with a property management company, theoretically, they are suppose to withhold money on your behalf which trigues you having to file a return.You may be required to file a 1040NR which is different than the 1040 form that Citizens / Residents file.

It's opinion based and requires market research, but in general you need to compare prices vs. market rent, size, condition, and homeownership vs. number of rentals.

I would not go online to get medical or legal advice from randoms. 

There are some crime maps available online too.

Some umbrella companies have switched their base insurance requirement from $300/300 to $500/500k. 

No professional is 'necessarily required' but it is normally a tradeoff between time saving, assurance that things are done correctly for a cost.For me, i can paint one of my rentals, but i decide my time is better spent elsewhere.Best of luck.

I am not sure where to begin. with your septic and well you'll need to do site layout first with a land planner or the county. after that you'll need to check setback requirements and design plans and start budgeting with a builder. once you have a confirmed plan set and budget broken down and builder selected then you can talk to banks. most people think it starts with banks