I think the points raised in the five questions would mostly come up in underfunded projects. Sure, you can have everything you're willing to pay for. Especially things like
> Can I adjust my feature set and specifications as we go?
Most project budgets for SMEs and startups are guestimated by a business development team, therefore underfunded.
You'd be VERY lucky as a firm to be communicating with a technical, who has an actual idea about scope and the time it takes to iterate a "small feature", if they're coming to you for a project.
> Can I adjust my feature set and specifications as we go?