If I build at $100 sqft ( a guestimate) then my total cost will 220K+90K = $310K , let's say $350K with surprises.

New construction probably sells for 3x construction hard costs, soft costs, interest, etc will probably eat up total of 50% of exit value.

It should rent for 1300 total (650 each). 

16 units has to be 200k+ in total at min.I would see if you could get a HML for this (rehab to pass underwriting) and then refinance?

Everyone is jumping on the bandwagon of house hacking a MFH which is totally understandable, as that's how I got started.

If it's totally cleaned out, then it's a given he or she has really moved out. 

Yeah, fixer-uppers can be quite the project sometimes, totally worth it though!

The records or other documentary evidence must support all the following: The amount of each separate expenditure, such as the cost of acquiring the item, maintenance and repair costs, capital improvement costs, lease payments and any other expenses.The amount of each business and investment use (based on an appropriate measure, such as mileage for vehicles and time for other listed property), and the total use of the property for the tax year.The date of the expenditure or use.The business or investment purpose for the expenditure or use

You just defer, not totally avoid (can avoid 15% if held for 7 yrs).2) To completely avoid the capital gain on the investment made in the OZ if held for 10 years.  

-How much are the 18 homes worth in total?