Anyone here successfully navigated Spain’s long term visa bureaucracy? I have questions …

I’m in a weird spot career-wise where it’s unclear what kind of visa I should apply for. I have enough passive income to apply for a non-lucrative visa, but I’m working on several side hustle projects that aren’t making me any money right, but which will start making me money in 6-12 months.

I’m trying to be respectful and comply with Spain’s requirements but it’s unclear what visa I should apply for. When I asked my local consulate, they were of no help. Any suggestions?

Other questions include:

• Why would I secure a rental contract, purchase health insurance, and purchase a flight tickets there and back.x when I don’t even know if I will be approved for a visa and for how long. It sounds like a catch 22, no?
• Do I have to apply for everything here in my home country (USA) before going over to Spain? Or can I travel to Spain in a 90 day visa and then apply for a long-term visa once there?
• I want to fly there and immediately walk the Camino, then rent a flat … So what do I put on my visa application as proof of residency?
• Is it worth doing all this myself, or should I hire an agent to do the footwork and paperwork for me?

Thanks in advance for your input!