$5M cash exit at 24, 6-12 months no income ahead — how to structure and manage this?

I've just exited a startup with $5M net cash at 24. I'll be exploring my next venture for the next 6-12 months with no income, living in SF where my expenses run ~$100K/year. I also plan to do some angel investing.

Specific questions:

1. Self-manage vs. fee-only RIA (AUM-based) vs. hourly/flat-fee advisor for initial structuring — what makes sense at this asset level? Any recommendations for finding a good flat-fee advisor in SF bay area?
2. What's a safe annual withdrawal rate to cover both living expenses and angel allocations without eroding principal?
3. For the liquid portion I need near-term, what's the right vehicle?
4. For the rest — index funds, private markets, something else?

I don't have any experience managing assets at this scale and want to get the structure right before doing anything. What would you do?