I prefer buy and hold.

However, I would like to know if anyone could recommend a good book on the topic of communication and interaction with motivated sellers.

I prefer a solid 20%-30% down payments. 

This one is personal preference, but I would never work with an agent without that agent being able to oversee, or seamlessly hand-off rehab work, and property management.  

As I eluded to in my post (or attempted), I live 40 miles outside of Mpls and prefer to keep my first property close by for simplicity of management and control. 

The "personal gain" for your Realtor in introducing you to a preferred lending partner is likely to be limited to transaction comfort and accessibility  as well as referrals to other buyers/sellers. 

Is there anything like a short explanation on how we can sell or create a second class share, preferably non-voting shares in exchange for financial backup up to 500k?

If you have a 12 unit that is generating positive cash flow, and your bank is telling you they prefer to gamble on a flip... that's silly.

Once you calculate the actual value of the home based on the comps, you take 70% of that (or whatever your local end buyer's prefer) and subtract out the repair costs.

I don't know squat about NY RE, but it sounds like these sellers are trying to exclude folks using HML, and look for only a) All cash buyers or b) HELOC buyers.If you want to play in this arena, and that is what is going down, I'd suggest opening a HELOC on some other property you own with the highest maximum credit line that your equity position will allow but a $0 current balance.Offer accepted, max out the HELOC, funds arrive next day, show proof to seller.Then you would use the HML to pay off the HELOC a few weeks later, if you'd prefer that the debt be secured by the subject property.