If he keeps his end of the deal, you give him the equivalent of a referral bonus.  

If you bought a $500k property with a cap rate of 5% you'd get an NOI $25k/year, equivalent to getting interest of 5% on a $500k investment.Then you subtract your financing costs from the NOI, and that would be your cash flow.

In July, a renovated house across the street sold for a sq ft equivalent of $589k in 2 days.

Depending on the amenities in the communities, HOA fees can range from a reasonably equivalent cost to exterior maintenance/landscaping to devouring your entire profit margin.

However, the moment he is late, be sure to post a 3-day notice, or the equivalent in your area, and start the eviction process. 

Put the money into VTI or the equivalent while you save up.

Moreover, the amount of research you will need to do in order to have a chance of making money out of your  area is the equivalent of a full-time job. 

My goal is to own "200 units by the end of 2017...or its equivalent in flips."

But the profit will likely not be equivalent to a strong flip.

Comps for equivalent properties in the area or in the high $300k. property is currently generating $1400 a month, though can easily generate $2800-$3000 with good repair (based on surrounding comps).