Hello! By "suspicious" I didn't mean to imply bad intent, just my doubts that you could offer a fair (i.e. competitive) salary (any benefits, or is it BYOHealthInsurance?), and also that you were sufficiently well-capitalized to fund the business. Underestimating the necessary capital is one of the leading causes of startup failure. So if I were approached with an offer like this one, I would not be getting my hopes up until I heard some numbers, and I would be skeptical unless I saw a pretty thorough plan with budget and expected revenue. But that's just me: I am fairly risk-averse.

Re "final say": Ultimately if you're business partners with someone you both need to be happy. And you both have an incentive to balance polish with shipping. Still, if you were a client and not a business partner, and you were paying me on a fixed bid, I'd want a spec up front, not at the end. (If you were paying me hourly you can have all the revisions you want.) If we were potential partners, I'd be asking myself what the risks are if you prove difficult to work with--for instance, what am I giving up to join the venture? And do you have a history of managing software projects that would reassure me you're capable and reasonable? (Any recommendations from developers you've worked with?)

In any case, I wish you good fortune on your venture!