My question to Mike is purely mathematical: how much market must loose in order for me to start losing money from my paycheck?

But from a purely objective investor perspective, you will have an easier time and more consistent cash flow with fewer doors in higher-end areas. 

When I run my numbers on prospect deals, I run them as if I were purchasing it as a pure rental/investment property.

@Jorge Leon Jr, I understand the ease and sense of security that comes with not having a mortgage, but from a purely financial POV, it isn't ideal.

Live there while you're at school, then either keep it as a pure investment property or sell off and move onto something else?

There are probably a small handful of places you could find these type of economics (pure cash flow and little to no appreciation potential unless the cities really rebound) = Detroit and St.

Again I can't speak to how much intrinsic satisfaction you get from your work, however - building something from scratch, or re-vamping something real and tangible that has a big impact on a community I'd think might provide a more meaningful day to day.On the pure financial, per above - let's say as an example you could create 200k-250k worth of net worth (less liquid, sure) per year - producing 30k/year income at year 2. 

If they are marketing and bringing you new properties, then a percentage or a flat finder fee for each property may be appropriate.If their role is purely administrative and they are simply managing the rentals once they are received, then I would only consider a periodic bonus based on the increased workload.

A pure luck play from a Craigslist Ad resulted in my very low offer being accepted.

And my recommendation is purely based on my personal limited experiences.