And of course working smoke alarms (and if gas, carbon monoxide detectors).  

On their application they both said they're non-smoking, however I recently found a few pieces of evidence that one of the tenants has been smoking outside.

One interesting find during the inspection of the "in law" suite was that no smoke detectors were installed in the furnished basement.That being said, this has me concerned about the potential quality of work that went into the rehab, and whether or not licensed contractors/personnel did the work?

Is it up to fire code (may require hard wired smoke alarms, exit lighting, etc.)?

But,they smoke inside (against the lease) and therefore I have said I wouldn't replace doors and windows with them doing that because of additional damage it causes.Other than that, when they didn't pay that would've broken our lease I would've thought.

If  you had quality finishing work but, picked dated and dark looking finishes I have seen them influence an appraisal.  

@Nathan G. it is always bad when a tenant goes dark.

Things that we see as recommendations to fix after include:- cut back overhanging branches- add railings on stairs- fix cracked/broken driveways or walk ways- repair roof issues - clear debris from outside or inside- upgrade fuses to circuit breakers- repair broken alarm/smoke detectorsYou should discuss the inspection with your agent. 

Been calling and trying to Zoom with people but would like focus my efforts instead of shooting in the dark.

LOL, love how many words are used to say no smoking.