So when you receive a payoff from the borrower, amounts above your cost basis is a gain.  

How should I analyze the borrower as a flipper?

That income will be aggregated with all other income, properly accounted for and used to offset the Borrower's liabilities.  

Take the gross income, x .43 then subtract reported monthly bills such as car, credit cards student loans child support etc. whatever is left is what the seller, or borrower, can qualify for. in other words...have them complete a 1003 with a lender to see. 

A partner and I will be borrowing money for a unknown rehab project.

I am very interested in lease option deals, wholesaling, fix and flip, rental property in the next few years with tenant buyers in them..My first main question is already posted on here, involving a private loan for a partner and I to rehab a house then list and sell.A partner and I will be borrowing money for a unknown rehab project.

Simply providing timely updates and pictures of how things are coming along.If you are planning to, or if the borrower wants you to take a more active role then getting a split of the profits makes more sense. 

and then like what happened to many in 08 and 09.. those that banked with the big banks got the cold shoulder many small community banks ( if they did not go under) stuck by the core borrowers...

A mortgage is basically a lien against a property that says "this property is mine until you pay me back all the money you borrowed or this note is somehow satisfied". 

to "borrow everything possible!"