Owner said has long term tenant on one side of 9 years , building has had  great rental history.  600*2=1200 monthly1200*12= 14400 yearly taxes/insurance =2800 yearlyrepairs/maintenance 10%= 1440vacancy 10%=1440 14400-2800-1440-1440=8720 NOI20% down on 99000 @ 4% interest 30 years =19980 mortgage payment roughly 382 a month /382*12= 4584(NOI )8720 - (debt service )4584= 4136 monthly cash flowcash flow 4136 / (money invested) 19980 =20% ROIAm i missing anything here ?

I'd like to put $100K down, and fund the rest with a HELOC.

Not jewelry, Computers, Guns, iPhone's, Dental Services, ….. just shipping and paper services.Now, one half of the building will be empty in about 40 days, so there will be a totally empty 1000 sq. ft. very nice open room / office available.

It is certainly possible to combine a primary residence exclusion and a 1031 exchange to completely eliminate most and defer the rest of the tax.However in your case with only 1.5 years of depreciation it might make more sense financially to simply forgo the 1031 portion and pay the depreciation recapture.  

When we asked for the down payment back he wrote a $600 check and said the rest of the money went to his costs... $1400 for gas and a 6x6 inch block of concrete?!?!

Rest is done with hard money.

I’ve signed with a Property Management company with realty services.

So my strategy would be to get a 70%LTV loan and mortgage from a bank and find maybe 1-3 debt investors to finance the rest.  

They did not reply for 5 additional days and when they did, they demanded full rent payment and sent us receipts for the appliances they bought and the cleaning services they used prior to us moving in. 

Multi investing is about income generating not appreciation.Make sure you maintain your property and keep your rents at full market rate and the rest is out of your hands.