How do I properly calculate these numbers?

Better to put in something more productive like a Solo 401(k) or SEP. 

Meaning once they get properly underwritten they'll be pressing DTI limits.Those two are not going to be reason the pent up demand gets exercised; if rates drop significantly and quickly it's for a net negative reason and likely job loss so those "pre" qualified and approved are likely on shaky grounds and buyer expectation shifts happen to the one's that are extremely well qualified. 

There is no 100% guarantee out there.Managing your property properly and having great insurance are probably the two best ways to protect yourself.

They could have had better affiliates who do a better job on a turnkey property.ofcourse you are right that I could have done my proper due diligence which I did.

There is usually a missed opportunity in most markets delivering housing products that are needed but not readily available and the Zillow data most rely upon does not tell this story.Get to know the members of a community, their needs, what steers them away from the housing that's currently available.

However, you must give both a 5 and 14 day notice (concurrently) which must be properly served, and it gets more technical from there. 

Take ownership of your mistake and learn to do the proper due diligence recommended above😊

Be sure to investigate the varying product types. 

The other which is where many of the syndicators do not do properly is what you discuss.