Go talk to people in the industry. Event planners, etc. Get to know your customer and their pain points before you start building anything. Also understand the tools they currently use.

Find a good electrical engineer and hardware engineer.

We always Start with UI/UX. Wireframes and HiFi designs. Every screen. Makes it easier to build.

Sounds like a low ball offer. I would continue to sell and grow the business. Hold out for something better. As for the investors - stick to what the written agreement says. Written agreement trumps verbal conversations.

Going into business with someone you don’t know is risky. Better check their background. Check their references. Also get stuff in writing. Also do equity —- earn it based on milestones. Besides the idea. Is the other putting in cash? Or bringing something else to the table? Need to deter in the value of each person contribution. Etc…

Deeper Deals — worst name ever. Was a bulk ordering website. Went out of business. I laughed so much when they told me the name.

Anything that can be shared and look good. Get the content right.

Most are PDF. PowerPoint saved as PDF.

Since you are developer - build using the skills you have. Depending on the product - no-code has limitations. Also no-code can dilute your IP and make it impossible to patent anything. If you need validation. Do some no tech solutions or code something really simple.