@Sander A Swenson welcome to BP, this is great place to be. You have some solid goals laid out.
1) As you've probably heard and seen through your research California is a tough place to cash flow in general and especially the coastal areas with housing prices, your best bet would be multi family units with deferred maintenance or get creative with an SFR to make the numbers work in terms of cash flow.
2). @Ben Tilbury pretty much summed it up on this one
3). You really need to get creative here and think outside of the box AND have an exit strategy in place before buying. In terms of long term hold properties you can look to STR, corporate housing, renting out garages as storage, etc. I know people who have considering renting a car out with there AirBNB as a package deal. These all require substantially more work but can increase cash flow. There's a good investment summit this weekend in Oakland put on by @J. Martin he and @Al Williamson are experts on these investments (Event Link: SF Bay Summit or Bigger Pockets Event Link). The CEO of Bigger Pockets will be speaking as well which will be cool to hear.
4). There's a ton of thought on this but nobody knows when/why/how bad/etc. about the next recession so it shouldn't affect your current investment strategies. Buy right, like Ben said be prepared to buy low when it does happen, and possibly look to invest in areas less prone to market corrections (ie. midwest markets)
Welcome to the community down here, I'm actually working with Ben on a project right now. I'd love to meet up sometime and talk real estate and goals in general, always good to network with like minded people.
Cheers
Tim