Describe the client, the problem, and your approach, and get a structured proposal covering understanding of the brief, scope and deliverables, timeline, pricing, and what's explicitly out of scope. That last section is what prevents scope creep later.
Your result will appear here.
Leading with a clear grasp of the client's problem before talking about yourself, and being specific about deliverables and exclusions so expectations are unambiguous.
Usually yes. Proposals without pricing stall. Presenting options at different scopes often works better than one figure.
No. A proposal is a commercial document. Have a proper contract reviewed by counsel before work begins.