(Note however that the notice you posted concerns violations observed in March 2017.)

You need something to protect you against all the eventualities - like another broker stepping in and claiming "procuring cause" for the buyer.I'd talk with your broker and get an attorney to draft that agreement.   

Some things you can do beforehand are: research the area to understand the local demographics and whether any similar type businesses have previously been approved, whether there are any currently in operation in the proposed area, if there are - evaluate what they are doing right or what they are doing wrong (how are they similar or dissimilar to your proposed property), reach out to the neighbors and get their input and try hard to get them on your side, reach out to the police department and listen to any concerns they might have, etc. 

My biggest concern is selling these solid, cash flowing properties and then not finding that next larger property.

., Refis after completion of of a 1031 exchange have generally never caused an issue. 

Our seller was interested in cash flow on a monthly basis and wasn’t concerned about overall profit margin as much.

While I've been intrigued by the ability to invest in notes from anywhere, it is what concerns me the most about making the leap into it.

I have read that most of evictions are caused by tenants already living in the properties.What are your thoughts on this?

I spent the first solid week of the new project writing SOW sheets for the numerous trades (I do NOT miss those days, lol).I think the issue with residential renovations comes that these lengthy scopes might actual have the basic sub or contractor (think one/two guy company with a few laborers) concerned with working for you.

Our concern is that it seems that in the past few years there has been very little appreciation.