If there is something going on that is making you fearful then you may want to get law enforcement involved.

The capital stack especially in CA is VERY complex and typically involves everything and more that you mentioned.

Enclosed a few pics for your reference.Should I involve the HOA?

One of the biggest challenges for everyone involved is being on the same page about the actual time required for maintenance.DIY landlords rarely properly track their time when it comes to property management in general - tracking their true time invested in maintenance is where they perform the worst.Investors that hire PMCs are rarely any better at understanding the true amount of time maintenance takes.

So this involves hiring an architect draw up plans ($1,000 - 3,000 if I had to guess).  

I personally have no connections with anyone who is involved in this niche and I'm wondering how other people have started their journey.

Many real estate agents dabble in property management without fully understanding the complexities involved, making it risky to work with them.

I work on projects across multiple states and have a strong network of contractors.Regarding when to involve a contractor, if it’s someone you haven’t worked with before, I’d suggest waiting until after the inspection.

who are involved in wholesaling or other real estate ventures.

In addition, the book keeping and legal involved with a syndication process is greater than if partners are not involved.