Since it's now been deemed safe, do you think it's still worth having future tenants sign a waiver and release just in case there is any incident within the parking structure, or, since it's been deemed safe, should we just not worry about it?

It helps them clear their past due balance and often times they pay several months into the future too.

Given the current rental property mortgage rate is well above 7.2, and it looks like it is not going to go down any time soon...i expect it will take 3 years to go down by 2 pp...Is it still dumb to buy a 500k investment property full cash and plan to cashout refi in 2,3 yrs? 

In regards to partnership, make sure you have every duty, responsibility, and expectation outlined in the partnership agreement.

How many days do you expect on market?

I cerntainly wouldn't want you to expect time and labor and covenience for free or at a discount but on the same note I wouldn't want you to get price gouged, lied to and taken advantage of either.

Welcome to BP @Mariana Diaz and I wish you all the best in your real estate goals and future.  

Walking away is a good strategy if you think they could come back at your terms, in the future, or at least try to reopen negotiations. 

He missed that deadline, so stick to your consequences and notify him that the lease will not be extended or renewed so there's no confusion.Personally, I would give him notice of termination and expect him out no later than 30 days from notice because of the noise, potential violence, and failure to communicate.

Probably an extra clause in the lease should be added in the future to insure the tenant accepts the property as is when it comes to these internal elements.