The house actually is laid out where it can easily accommodate the 14, the halls are 4' wide, there are two stairways that are pretty open, the house has over 20 windows that open and are at a height so that someone could escape to the roof or onto the covered porch, ladders for throwing out a window, hard wired smoke detectors, etc.

I'm looking at a similar situation with a two-family in Troy, NY ... double doorway in front which enters into a hallway/stairway leading to the first and second floor units.

He signed off on the system which we had professionally installed.Something the fire inspector pointed out that he did not indicate in his initial inspection were the walls going up the stairway of the common area. 

Call local city housing dept.Once a year they inspect the property for tidiness, health and safety concerns(e.g. railing on stairway), fire detector etc.

That being said, I was wondering if little things like; creating storage under a stairway, adding recessed lighting, automated technology fixtures/features (Alexa, Google, etc), little things like that.

It takes years to build a stairway to heaven.

if you just wanted to cover your rear, send a photo of it to your insurance agent and ask him in the email if you need to get any additional coverage for the stairway. 

Actually, the more I think about it, CA landlords might want to start including a clause that says just that - the landlord is not liable for PG&E outages.I found the following from this website: https://www.stimmel-law.com/en/articles/landlord-obligations-habitable-premises-basic-california-lawThe Statute:In terms of residential leases, in order for a landlord to be allowed to place rental units on the market, the landlord must first ensure that all of the following conditions which make the building ‘fit for human occupancy’ are met: [Civil Code Secs. 1929, 1941]Effective waterproofing and weather protection of roof and exterior wallsWell-maintained plumbing and gas facilities compliant with law in effect at the time of installationWater supply compliant with applicable law that is capable of producing hot and cold running waterWell-maintained heating facilities compliant with applicable law at the time of installationWell-maintained electrical lighting compliant with applicable law at the time of installationBuilding, grounds, and appurtenances kept sanitary and free from debris and vermin at the time of rent or leaseSufficient number of receptacles for garbageWell-maintained floors, stairways, and railingsLocks conforming to code [CA Civil Code Sec. 1941.3]Dead bolt lock on each main swinging entry doorWindow security or locking devices for windows capable of being opened

(that part impresses me the most. lol) It was the ultimate pain to get it down to our basement (the stairway was way too small so it had to be taken apart and rebuilt by a professional) but totally worth it, in my opinion.

I would find out what your local building code is for stairways, step width, stair tread, riser height and incline,, just as you think.. this is complicated. just because it's grandfathered in doesn't make it less of a obstacle just makes it a legal obstacle that someone can always find a lawyer to help in filing a suit..