The other owner has not begun pursuing anything except calling me. 

For many it does not work (my partner and me might end up as part of that bucket someday, that is yet to be determined), but there are always exceptions to every "rule" (or popular opinion).  

If you have to get a 3.6 loan just to make this property even come close to penciling it sounds like a bad deal to begin with.A possible exception would be if this property was old and sitting on a bunch of land to develop to a higher use or sell off later on.  

It's very simple and this samee deal allowed me to buy my 5th home last year, in the same position, except that I was living in South korea then and my job was there.

Since every single rental home in the neighborhood had "Days on Zillow" of less than a month, I was thinking that the rents were probably set about right...except for one house.  

Now there are a few exceptions but not many.

But over time, this market has enough jobs and enough people in the rental market that it'll reach an equilibrium and vacancies shouldn't be a substantial issue even for buildings with similar rents.In essence, there isn't an answer we can give you except to know the market youre looking to buy in, and determine how X number of units in X property class will impact you.Smaller markets will obviously have more significant impacts if a new, large building is built.Hope that helps.

There are some exceptions to this but no need to go off topic here.

There are exceptions to almost every rule.  

It's basic addition/subtraction, with the exception of how to amortize a loan to find the loan amount, but you can look that up online.For reading I'd suggest some or all of the following:-Rich Dad Poor Dad (Not really a -Cash Flow Forever-The Millionaire Real Estate Investor-The 4 hour work week