Everyone's personal preference is unique but as Thomas S. mentioned, I would never pay off a mortgage.  

Affordability is therefore a better metric IMO as it combines median price, median income, and interest rates rolled into one.

In the beginning, do not do anything unique.  

As for comps, I use a combination of Zillow, Trulia, Redfin, Realtor, and the median sales for the zip.

I cannot see the HOA, Ins & utilities adding up to 900 a mo combined, but am waiting on this info as we speak.

If I'm reading that correctly they have combined 65K+ of PAST DUE debt?  

There is always risk associated with a rental property but since you will be living in one side and renting the other the potential increase in cost would be whatever your combined mortgages are minus what you have been paying for your current place.We did a similar deal in Kansas.

So I've got a unique situation.

It sounds like you have worked with people, so you could probably manage the tenant issues as well.If being a landlord is not your goals, your background may make you well suited for a live-in flip, where you buy a fixxer-upper property and make the improvements while you live there (forced appreciation); then after a couple years, you can take advantage of the tax free sale.Both of those strategies combine with something you may be looking at and need anyway--a place to live of your own.

Some combination of ARM, higher rate, and points upfront, will apply.All of this should have been brought to your attention back when you were seeking preapproval, this is commodity/common knowledge among lenders.