Moving In With Off-Roster Handguns?

Hi there! I'm going to be moving to the Bay Area from Seattle in a few months, am in the midst of trying to understand the tangle of fun gun laws in CA, and could use some help!

My current understanding is that if I already own legally purchased handguns not on the roster, I should be able to bring them in (without >10rd mags). I've seen some threads around the topic here, but can anyone specifically confirm the legal situation?

If I can keep what I've already got, I'm looking at picking up a few off-roster items I've had my eye on before the move. I'm not planning on reselling anything, but it'd be nice to know if the option would be open down the line when I'm making the investment.

On a related note, what am I looking at in terms of a local shooting community? I'm getting into USPSA/IDPA, Bullseye, and enjoy precision rifle (rimfire only for now). I'll be living somewhere between San Mateo and Santa Clara (partner's PhD internship at Stanford is bringing us). I'm used to driving a bit, being from Seattle - we just had our last gun shop legislated out of the city with a taxation maneuver this year. Speaking of which, how's the ammo market?