Every where you turn there are STRs going up on the market fully furnished because they couldn't pay the mortgage and bills with the rental income. 

If this is what sub2 is, then why are people paying tens of thousands of dollars to learn this process?

Or how much do you pay in rent.  

Yes I know people spend hundreds of $ for Best Ever and other meetups just to meet other LPs/GPs, but those are in person meetups where they have to pay for a venue.

I would like to make sure the siding is presentable before paying for an appraisal.

You can probably try this yourself with a letter or maybe even a phone call.If that doesn't work pay an attorney $400 to write a letter. 

Depending on what softwares you use they can usually pay for the background check themselves.

If you're doing a rate and term refinance, there's typically not a seasoning period but again it's common for lenders to require it be rented first.If you're doing a DSCR cash out refi, it may not need to be rented first but you're probably paying a higher rate.Your best option is to call a loan broker you trust and go through the options based on your current situation.

If you don't occupy the property, then you'll have to pay 20% down.

.- 95% of folks in pre or post NOD want to stay in their house, keep their house inspite of them 100% will loose the house at the auction.