Non CHL holder transporting a handgun by car into Cali from out of state: have it unloaded and stored in a safe?

Would a small, keylocked fireproof safe be OK?

The safe must not be concealed, right? If one is in a van (no trunk), does this mean the safe can't be obscured under blankets, luggage, etc?

10 round magazine tops, correct? Ammo and unoaded magazine stored separately in a backpack OK?

Am I missing anything? Thanks.

A safe?  No, you don't need a safe.

In vehicle, pistol must be unloaded and in a locked container.  Container must be "secure".  Basically, it can't be something you can easily just force open to access the pistol without unlocking it.  A bag, pocket on a bag, or case that can be locked such that it can't be opened to access the pistol is sufficient.  A safe is overkill.  Can't use the glove box, utility box, or other compartment accessible from inside the vehicle, even if it locks, as a container, though.  A pistol stored in one must still be in its own locked container.

Magazines can be loaded if you want.  Can be with the pistol (just not in the magazine well), or not.  Can even be on your person.  No need to separate ammo or lock up ammo or magazines.

None of the above need to be left in the open.  In fact, I recommend against it.  Better for a cop not to know, because CA has a 4th Amendment "exception" for firearms, allowing a cop to do a search without a warrant, consent, or probable cause if he knows or suspects a firearm is present so that he can inspect it to ensure compliance with the transportation statutes.  If you get pulled over, the cop might be cool, or he might give you a hard time or worse.  I also wouldn't mention it or tell him you have one if asked.  No duty to inform here.  The more densely populated the area, the better it is to be discrete.

When not in a vehicle, the same requirements apply, but you also have destination requirements.  You have to be traveling directly between authorized locations (range, shooting area, FFL/gunsmith, home/residence, private property where you can have a gun, campsite, etc.).  You can't just go wherever you please carrying a handgun this way, at least not legally.

Open carry is allowed in unincorporated areas where discharge of a firearm is not unlawful.  Due to a prohibition on shooting on or across roads, this bars open vehicle carry unless not on any kind of official road.

Concealed carry is allowed while hunting.  Must be unloaded when traveling directly to or from hunting.  The rule above apply beyond that.  IIRC, this also applies to fishing, but I'm not sure about that.

If camping, your campsite is treated like your residence, and you can openly or concealed carry within it.  Hotel is treated like your residence as well.

Can't legally bring in magazines with a capacity larger than ten rounds.  Pistol cannot be considered an assault weapon.  This includes merely having a threaded barrel.

Thank you.

Agree.  I'd also suggest the "locked container" be kept out of sight.  There are a lot of areas were vehicle burglaries are possible, and some quite common.  You don't typically want something that looks like it might be valuable visible through a window.  It's a bit of a problem, one might want to be easily able to move the locked container in or out of the vehicle at a destination but a "safe" or similar lock box secured to a sturdy part of the vehicle could discourage or prevent a smash and grab.  Likewise fussing something in or out of a more secure box might a problem and more obvious than necessary.

I would definitely suggest leaving anything and everything out of site.  When we used to frequent the SF City I would wrap up everything down to the phone chargers, FASTrak device, loose change.... everthing out of sight.