Make sure stair railings are secure, stair treads are in good shape and that all smoke detectors and CO detectors have a new battery and are working.

Now, I just buy reconditioned units around half the price.

While that is absolutely no substitute for a battery of surveys (soils, etc) performed by the appropriate engineers, it can help get you a basic idea about the property and what kind of work might be necessary.  

For example recently I had two and these are their charges:PERSON AAGG ASSAULTW/ DEADLY WEAPON WITHOUT INTENT TO KILLTOUCH OR STRIKE/BATTERY/DATING VIOLPERSON BCORRUPT BY THREAT PUBLIC SERVANT OR FAMILYDUI ALCOHOL OR DRUGS 1ST OFFENSERESIST OFFICER-OBSTRUCT WITHOUT VIOLENCEThis is before viewing the apartment, before actual application. 

I just move them around or get the Kwik Set smart  rekeyable locks.keypads are more expensive, more prone to break and the tenant may call you when they can't get in because the batteries died.

They take a 9v battery as opposed to 3 AAA’s like Weiser.

During those inspections check the fire extinguisher and change the smoke detector and carbon monoxide batteries (Unless they are those 10 year batteries then just test).Personally I would rather have them and have them documented to be working at proper intervals than not have them and experience a loss of life or full loss of property.

Buy the fuel and/or batteries through the business account.

I am trying to determine if there is any regulations, state or local that governs fire extinguishers in terms of type, how many, and location.I know there are city building codes on fire alarms, smoke alarms, hard wired or battery which is dependent on when the property was built as well as whether it's a SFR or multi-family dwelling.However I couldn't find anything on fire extinguishers. 

And, don’t forget to check the light bulbs and batteries.