@Marcus Auerbach Yes, your assumption about my question is about correct lol.

But assumption of the loan doesn't cost you anything. 

@Nolan Gray  I will make a few assumptions about size and guesstimate as follows:Lot $50,000 (may include removal of existing building)Impact fees, plans, overhead $20,000water, sewer, gas, electric $20,0002 commercial units, semi-finished = 4000 SF x $140 = $560,0006 units = 6000 SF x $160 = 960,000total: $1,610,000Cost of new construction significantly exceeds cost of existing buildings plus rehab.

Yes, you should have :)  This perfectly illustrates the danger of getting or giving tax advice online from incomplete information and assumptions. 

So just a blanket assumption of 50% might not be the right number esp if inventory is low in your area which can increase both turn times and length of stay.

The water assumptions make sense and helps a lot ! 

Federal law allows relatives to assume an existing mortgage after the death of a borrower; bank cannot object so this is not a "subject to" issue. Has anyone had experience with doing such a transaction,including what...

I tend to agree with @Mohammed Rahman that she won't go for the cash for keys, see an attorney familiar with Suffolk County evictions to find out your options, don't make any assumptions. 

just wondering if I'm blindly making assumptions if personnel would start pouring in or am I just chasing my assumed market

Hey team - trying to underwrite my first property and im under the assumption that you would spend about $250-350 / unit / year for "maintenance fees" associated with the apartment complex.