Assume a couple of months of vacancy, consider potential unexpected repairs (like HVAC or plumbing issues), and test the numbers with rents dropping by 10-15%.

A couple of days?

I started out with the other guys, getting a couple LLC's done but became disappointed with them because of response time, and conflicting information.

When you own a couple of units, the odds of there being unexpected vacancies that overlap each other are usually low, but when you acquire more and more real estate, the odds of tenants moving out around similar times increases. 

I owned one for 13 years but it was a STR for only a couple of years prior and the other for 7 years and was always a STR.  

If you have a network of a couple consistent buyers, that's all you'll ever need.

Hi everyone,A couple of weeks ago, I noticed a seemingly vacant and distressed property near my current residence.

So every couple of years we get to the point where we can’t accept the PM company’s performance and we have to look for a new PM and hope we find a unicorn. 

And got a couple houses from random lines of credit from banks.

No way to say for sure since each lender is different and I have no idea of the terms you need or your FICO, but it is typically the prime rate plus a couple of points.