Spending 55k with projected rents of $1500, say 500 per unit.  

More important than the structure, however, is to take a deep dive into the sponsor’s financial projections and their historical actual performance versus their projected performance.

My question is, should I be my own GC / Project Manager and just hire subs?

Either for guidance and/or to exchange deals- You also want to network with the various tradesmen you'll encounter with your projects, like contractors, home inspectors, title companies, investor friendly realtors, hard money lenders (especially until you gain access to private money).

Being a school teacher I have summers to do big projects.  

I use Craigslist and Airbnb and have had success finding good tenants on both sites -- mostly traveling nurses and some IT professionals doing temp projects in Denver.

I did hire this contractor but they walked off the job and I had to finish the project myself.  

The forecast result is a projection for annual total sales increase (total 2018 existing-home sales vs. 2017) and annual median price increase (2018 median existing-home sales price vs. 2017).

Fix and Flip - We just finished our first project which went anything but smooth.

This project the bank wanted to be under 70%.