We removed almost all of the charred material, had a fire damage cleaning company come in, and of course disputed of smirking fibrous.

The debris removal is also unclear to me what this is. 

They really don't want you to remove rental units from the system. 

This made me think of a better solution: you know how Amazon sells its tablets with advertising built in, and if you want the advertising removed, you have to pay more?

If this is the case, the structure needs to be temporarily supported, the primary supports removed, the failing concrete excavated and a proper footing poured to support the load.

Could it be necessary to also re-paint the walls and remove the acoustic ceiling to completely eliminate the smell from the previous tenants? 

The tenants do have access to the basement though because they have a ton of junk down there.My question is can I ask them to remove all of their items from the basement and change the locks to eliminate their access to the basement?  

Estimates for removing the tile are about 10K, so I'd prefer not to remove it.  

i would go in the basement or crawl space below it and see it there is another shut off valve on this line. if there is, remove the piping after that valve and to this one. cap off the lower valve and leave it in the off position. no need to have this thing sticking up thru the floor if you are not going to use it here

Will ultimately replace cabinets next yearRooms:  Paint over walls, remove popcorn ceiling.