Need guidance with seller financing on a commercial property

[Jaston Robinson]

Hello BP I recently came across a lead in Central Falls, Rhode Island. This deal is two 3 families on one lot (Cant NOT subdivide). These buildings are completely paid off & have been in the seller's family for almost a century! Little maintenance however, there are some big capital X (siding one house, 3 unit rehabs, potentially hard wire smokes in each house & a junk clean out). My strategy is BRRRR, is that the best plan?

The seller's situation: she is gearing up to retire & would like to use the money from the houses to put towards a condo else where. She also does not have the ability to do the updates to make the house market ready. Lastly, she is requesting to staying & pay rent for 3 months while she finds a new place to live. 

My questions: First what are y'all over thoughts & advice? How can I get an accurate purchase price for this property where I'll be able to refinance into a low interest loan after the rehab? What will that refinance look like? & how does the seller get paid off? How can I combine seller financing & other forms of financing to make this deal happen? 

Thanks in advance