He requested half of the money ($750) after 1st day and rest upon completion.

I just Partnered with my brother and his wife and we have in the agreement that if one should leave, the other has the right to first refusal and the purchase price would be 1/2 of what equity in the asset and savings there is at the time. and if sold the net income would be split in half. but in your case, whatever the percentage of ownership is would be the way to split it.

I found an old, large half a twin (side-by-side) that had been legally converted to a 2 bdrm apt on the 1st floor, and a 5 room "regulated rental" on the 2nd and 3rd floors.  

Would any of your responses change if it were possible to get a rental contract from the current tenants and put off maintenance for one and a half months until getting back from deployment?

It's a triplex that was converted to a duplex and it is currently priced at close to half it's market value.

I've kind of been copying my half-sister's dad's investment strategy, except he was even more negative cash flow with 10 year loans. 35 years ago he had 0 properties.

deal is 4, half-acre lots.

Then from there purchasing a multi family home such as a duplex and renting out the other half.

I purchased my first property 3 months ago, so there is a month and a half of home ownership expenses that will be included in my 2016 taxes.  

One might consider Bergen Lafayette or The Heights for similar product at half the cost.