Quoted: Ok, here's another ? for you... Does the ammo have to be locked up?  If so, must it be in a separate container?  Are loaded mags a no-no? Or can I put a box of ammo, a few empty mags, and my pistol in one locked case?

No the ammo doesn't have to be locked up.

Yes, a seperate container is good - I like the little cardboard boxes with the little plastic trays that hold the rounds.

Loaded magazines are good, just not in the gun rug with the pistol, or loaded inside the pistol.

When I bother to be legal I normally travel with the loaded magazines sitting in a milk crate along with my earing protection and other range junk. The pistols are kept locked in a gun rug - I use the 2 for $1 locks as they can be twisted open without the key if you need them quicker. The gun rugs are piled in the milk crate too. I toss a shooting mat over the long guns/milk crates to keep them out of sight (thieves mainly) and don't worry about it.

caselaw.lp.findlaw.com/cacodes/pen/12020-12040.html

Here's the penal code section that applies ... I'm going to read it again as it's been so long since I was actually concerned about following it ....

12025

Open carry is not concealed

Firearms carried openly in belt holsters are not concealed within the meaning of this section.

Let's see - you're not protected by 12025.5 because you're a temporary resident.

12025.5.  (a) A violation of Section 12025 is justifiable when a person who possesses a firearm reasonably believes that he or she is in grave danger because of circumstances forming the basis of a current restraining order issued by a court against another person or persons who has or have been found to pose a threat to his or her life or safety.

You're good to go in your hotel room, camp ground, and "place of business

No permit or license to purchase, own, possess, keep, or carry, either openly or concealed, shall be required of any citizen of the United States or legal resident over the age of 18 years who resides or is temporarily within this state, and who is not within the excepted classes prescribed by Section 12021 or 12021.1 of this code or Section 8100 or 8103 of the Welfare and Institutions Code, to purchase, own, possess, keep, or carry, either openly or concealed, a pistol, revolver, or other firearm capable of being concealed upon the person within the citizen's or legal resident's place of residence, place of business, or on private property owned or lawfully possessed by the citizen or legal resident.

Here's the nuts and bolts of carry in the car

12026.1.  (a) Section 12025 shall not be construed to prohibit any citizen of the United States over the age of 18 years who resides or is temporarily within this state, and who is not within the excepted classes prescribed by Section 12021 or 12021.1 of this code or Section 8100 or 8103 of the Welfare and Institutions Code, from transporting or carrying any pistol, revolver, or other firearm capable of being concealed upon the person, provided that the following applies to the firearm:   (1) The firearm is within a motor vehicle and it is locked in the vehicle's trunk or in a locked container in the vehicle other than the utility or glove compartment.   (2) The firearm is carried by the person directly to or from any motor vehicle for any lawful purpose and, while carrying the firearm, the firearm is contained within a locked container.   (b) The provisions of this section do not prohibit or limit the otherwise lawful carrying or transportation of any pistol, revolver, or other firearm capable of being concealed upon the person in accordance with this chapter.   (c) As used in this section, "locked container" means a secure container which is fully enclosed and locked by a padlock, key lock, combination lock, or similar locking device.

The next two sections of the law have many many examples of where 25025 doesn't apply to the requirements for transportation.

Ah here's some more good stuff:

12031.  (a) (1) A person is guilty of carrying a loaded firearm when he or she carries a loaded firearm on his or her person or in a vehicle while in any public place or on any public street in an incorporated city or in any public place or on any public street in a prohibited area of unincorporated territory.

Doesn't apply to:

(5) Persons who are using target ranges for the purpose of practice shooting with a firearm or who are members of shooting clubs while hunting on the premises of those clubs.

Definition of loaded:

(g) A firearm shall be deemed to be loaded for the purposes of this section when there is an unexpended cartridge or shell, consisting of a case that holds a charge of powder and a bullet or shot, in, or attached in any manner to, the firearm, including, but not limited to, in the firing chamber, magazine, or clip thereof attached to the firearm; except that a muzzle-loader firearm shall be deemed to be loaded when it is capped or primed and has a powder charge and ball or shot in the barrel or cylinder.

So no magazines attached to (in any manner) to the pistol. More permissions to violate at your place of business:

(h) Nothing in this section shall prevent any person engaged in any lawful business, including a nonprofit organization, or any officer, employee, or agent authorized by that person for lawful purposes connected with that business, from having a loaded firearm within the person's place of business, or any person in lawful possession of private property from having a loaded firearm on that property.

Here's the one I have use and wondered why the cops weren't upset that four of my five neighbors were all armed following a shooting outside our homes.

(j) (1) Nothing in this section is intended to preclude the carrying of any loaded firearm, under circumstances where it would otherwise be lawful, by a person who reasonably believes that the person or property of himself or herself or of another is in immediate, grave danger and that the carrying of the weapon is necessary for the preservation of that person or property.  As used in this subdivision, "immediate" means the brief interval before and after the local law enforcement agency, when reasonably possible, has been notified of the danger and before the arrival of its assistance.

Here's one for the ladies:

(2) A violation of this section is justifiable when a person who possesses a firearm reasonably believes that he or she is in grave danger because of circumstances forming the basis of a current restraining order issued by a court against another person or persons who has or have been found to pose a threat to his or her life or safety.

And a couple more:

(k) Nothing in this section is intended to preclude the carrying of a loaded firearm by any person while engaged in the act of making or attempting to make a lawful arrest.   (l) Nothing in this section shall prevent any person from having a loaded weapon, if it is otherwise lawful, at his or her place of residence, including any temporary residence or campsite.

And your punishment:

12034.  (a) It is a misdemeanor for a driver of any motor vehicle or the owner of any motor vehicle, whether or not the owner of the vehicle is occupying the vehicle, knowingly to permit any other person to carry into or bring into the vehicle a firearm in violation of Section 12031 of this code or Section 2006 of the Fish and Game Code.

A refreshing renewal of my understanding of the laws.