Just saw a episode of Judge Judy.. similar situation.. and yes,, the insulation needs to come out. you could get additional quotes,  remove brush, trash from exterior, any tree limbs that touch building, get exterminator in to bait and trap. next will be holes thru the ceiling from the rats.. any holes or vantage points on roof they are gaining access from, by A/C unit or vents that are damaged.. they are getting in some how and food source is active enough to keep them. 

Twice in the past 6 months, we have had someone (not the tenant) purposely damaging the AC unit. 

That being said, I want to be present as I don't feel they are going be diligent enough when it comes to accounting for damage to the property, etc. 

Issue can include land locked vacant lots, condemned or demolished houses, other government liens popping up, flood damage, fire, etc.  

The property has 3 stories, 2 of which were damaged due to a fire last year. 

At least if it's sitting empty, no one is doing any damage.

Will I have to replace the damaged windows and doors?

Extensive flood damage through out.

I've replaced all plumbing (freeze damage) and completely renovated one of the apartments.

I already plan to evaluate the carpet that's in there and check to make sure things like the doors have stoppers to prevent wall/door damage.