Recently, I’ve started adding a serving tray with items to help my guests feel more comfortable during their stay, including a QR code to an online welcome packet.

The government isn't mailing them copies of the violations.Assuming these items could have been discovered in a permit/violation search, it's actually your buyers agent, and the title company you should be upset with.

Of course we've had personal items left behind (wink wink), gun, etc.

Due to item 1, adding an ADU can require years to start achieving any return (once the accumulated cash flow recovers the initial negative position).4) Adding an ADU is a slow process.

Check big-cost items more carefully.

How dark do you go with cabinets and others items you mentioned?

Ideally something that is on web/app that'll allow me to keep track of different items come tax time. 

I can't say the tax balance is completely incorrect because A LOT of items can affect this number.

This is a big ticket item.

From what you have posted this isnt a demanding tenant issue... this is a "you didnt inspect the property very well and fix all the needed items BEFORE the tenant moved in" issueIf your PM is responsible for the post move out and pre-move in inspections, then they did a crap job.