When two or more people are evaluating a business model, they may desire to have a MOU (memorandum of understanding) to document their expectations about how they will share responsibilities and rewards, should they formalize the business through filing its incorporation.
What kinds of elements should go in that MOU?
I think perhaps:
I envision these being sections of a MOU letter, that all parties sign. This document is not strictly binding, but as typical to an MOU it does set expectations about what will go formally into writing for articles of incorporation, etc.
This may not be the answer you want to hear ... and to spend time negotiating an MOU describing the split of equity in a future company you may or may not wish to found together after you have discussed the business model is not necessarily the greatest use of your time.
Typically finding a business partner is like dating: you will often flirt with and date a few people before deciding you have 'the one' to get together with. To take the analogy further, what would you think of someone who wanted to negotiate the pre-nuptual agreement before going on the first date? That's what the 'negotiate the MOU while evaluating a business model' sounds like to an experienced businessperson. Let's decide to get married FIRST, then negotiate the pre-nup!
If you do decide to negotiate an MOU, here's some quick feedback on the points you raise: