Those rates are good for non-owner conforming loans. 

You might also be able to go hard money, short term and then refinance into conforming loan.

Hard money lenders typically charge much higher interest rates than banks because they fund deals that do not conform to bank standards such as verification of borrower's income, assets, or credit score. 

What is it that would appeal to the family who is conformably living in a house, undisturbed, that would motivate them to want to sell to you, let alone open probate? 

All conforming loans are going to use the same criteria.

Has the state landlord tenant law changed and your lease was modified to conform to the new law?  

Thus, you'll have to go with the conforming.

Address this at once and, if necessary, serve them with a lease violation notice to conform. 

The biggest issues I see is are you prepared to work out new parking arrangements if you were to build on it.Put it in the contract that the seller obtain a zoning verification letter that states that the existing uses are conforming and to tell you if there have been any variances granted for the properties.

This is where deeds and such are recorded.It is not the same as the property tax assessor/auditor/collector.Many counties have info online but there is not a uniform standard that cities and states conform to.