They will take an unpermitted, converted ADU and add it straight to the heated sqft, and bedroom/bathroom count when running numbers.

I can't count how many times I met with a seller and said my commission is X% (and I'll pay the buyer's agent out of that), and they replied that so-and-so says they only charge Y%. 

If the loan is serviced in this way, the loan won't count against your DTI after 1 year, should you want to purchase another home later on. 

Count your no's and eventually you'll get a yes

I think the answer to this question really depends on a few factors such as your current unit count, location of your properties, long term goals, and how much of your income is based off of your units. 

You will have the odd desperate seller like an American who took a mortgage on his US home to buy a property in the Dominican Republic and was counting on the rental income in the Dominican Republic to pay off his mortgage.

Remember, the seller is counting on this to close as well. 

A primary residence does not count for 1031 exchange purposes, so you would need to reinvest your capital gains from the rental portion of the 2-family into another property or DST in order to avoid paying taxes. 

With a $500k investment you could probably easily grow to a $1.65M, 6 units portfolio, with cash flow in excess of $2,500/mo, all while reducing your structure count from 6 to 2.

I found that the tenant has turned the property into a small farm. multiple pens set up with at least one pig, 4 or 5 goats, more chickens and ducks than you can count.