Hi Adriana, Typically, yes, the interest rate does spike, but depending on the borrower's experience and the loan size, you can still get loans at 80% LTV and rates in the 5.75 - 7.50%

You wouldProbably then need to pay Self Employment tax.  

If you where going to be able to recreate the orginal layout, you would of been able to do so by the clues left behind by remaining framing, be it the "honey" holes where the toliets once where, the sizes of the holes in the joist would indicate what pipes ran where be it hot and cold supply, toliets, showers and other industry standard tell tale clues. 

If you end up starting your own business and getting out of your current job, you'll generally need to provide 2 years of self-employed tax returns to support your income.  

Yes, management is more intensive, and 50 units is nearing the size of facility that having a small on-site manager could be a benefit for oversight, management and leasing.

If they pay a tenant portion, I verify employment, hours, and wage, or if it's benefits, be sure you have documentation.

Also, consider that when you do employ a property manager they do not shield you from vicarious liability. 

As you said, " a 1920's home generating 6k a month is overpriced at 720k" but a 1920's SF home that is smaller than one of the 3 apartments in the multifamily on a similar size lot for $450k makes that $720k option more realistic. 

I've personally explored this myself but my typical transaction  size is $3-$8M and the required check sizes are too small for their services.

@James Hamling The owner of Twin Cities Leasing gained his experience working at your employer many years ago.