If you don't know what a unit will rent for, you have no idea what you can pay for it and cash flow.I'll leave it at that, but stay focused, be willing to spend some time and be patient, and you should be able to have success here. 

Recently the lease term ended on one of my properties and the tenant decided to stay.

You must stay on top of it and be fully aware of the regular operations.

Even if you take the capital gains you would pay on the 210K into account, at first it seems the deal is one that I personally would not be comfortable with.

Nicely done @Brian Ellis - way to stay positive throughout the whole experience.

I believe it has to stay your primary residence for a year after but someone correct me if I’m wrong. 

The loan stays in the first owner's name but you are making the payments.

Usually, the Unpaid Principal Balance (UPB) stays the same and all of the arrears, additional interest, fees, etc. are added together and become the new "deferred principal balance."

The other tenant wants to stay and found a replacement tenant that would like to take over the moving out tenants spot.  

Battling against the World Series unforunately but the show is getting great reviews and ABC has just ordered 3 additional shows which is a great step in the right direction.We are so proud of our little Santino, he is doing great on the show and he has some very funny parts coming up in the next shows, stay tuned to ABC (channel 7 and also available on demand and on Hulu) on Tuesday nights 8:30PM Eastern and 8:30pm Pacific.