I was holding approximately 20 of their properties at that time, so you can imagine that unexpectedly paying out 20 interest payments every month was impossible.   

I estimated this to cost me $300,000 to scale.

Much of this analysis is based on the size of the land, how much it will cost to do the horizontal development, and then estimate the cost of the vertical build and ultimate value (aka "sale price")

Make sure you are using the estimated taxes shown at the Stark auditors site to check on them for next year as there are some significant increases coming!  

My biggest two cents is no one should flip unless they are the best at estimating ARV in their room--better than the appraiser, agent, lender--when that happens, your deals will fall into line. 

Also if anyone can explain how much I should have saved to get started and a rough estimate of how many single families I should have before moving on to small apartment complexes etc.If you have read this far I greatly appreciate it, thank you so much!

There are also many calculators out there that over estimate the cost assumptions or rent comps.

As a builder/investor myself some of your estimates seemed a little off to me, but those can be very market specific so its hard to say. 

As an experiment I invested $30k each in the 10 REITs which had (according to average estimate of NAV) the largest discounts from net asset value as per market price).

Have a future load analysis done and get estimate for what you want.