1. You need to either a) have an answer for "what happens if you get hit by a bus?" or b) create a product for customers to whom that doesn't matter. In general, people really _like_ being able to chat with the founder directly (lean into that! it's a superpower!) but feel very anxious about committing $X0,000/yr to you.
2. It will be somewhere between "vanishingly rare" to "non-existent" to feel like you are moving as fast as you should be. Instead of setting milestones and thinking about metrics, _especially_ in the early goings I'd focus on just spending as much time as you can on critical-path work (chatting with customers, chatting with prospects, improving core flows.)
3. This does not matter. I moved from Seattle to Richmond, VA last year and literally nothing changed about my business.
4. This is a very broad topic that is hard to answer concisely, but the closest answer I can give is "figure out how your first five users found your product and then figure out how to find more people like them".
5. Venture capital is a tool by which you exchange agency for large sums of money. There are a lot of great businesses that require more time, energy, and money than can be provided by a single engineer working for an indefinite amount of time; there are a lot of great businesses that can be built without those things. I would not take a lot of stock in any prescriptive answer that says you HAVE to take VC or you HAVE to bootstrap; it depends on the type of company you want to build and what you consider a successful way to spend a decade or so of your life.