Max:
First of all, do not discount the power of laughter
You will see a lot of feedback in this site about the loan-to-value percentages, and the debt service coverage that most bankers are looking for. There is also some information about the income approach to valuation. If you have some specific deal in mind, you can post the numbers and get feedback.
I don’t think you need a business plan for this type of transaction, financing income producing property in the commercial side might be a little more complicated and customized than residential lending, but it is the most cookie-cutter type of financing that commercial lenders do.
Good luck