Heat can easily force bed bugs into adjoining units and the proper way to remedy this is to treat the adjacent units weather they have bed bugs or not.

The source of the water is external and can be remedied with a sump pumb/perimeter drainage inside as well as a dry well outside.

Technically tenant is responsible for damages beyond normal wear and tear, there maybe some items still under their responsibility that you would consider to have them responsible for.b) Per lease agreement, the moment they breach the lease, the deposit goes to you, you are free to do anything you want.c) & d) Communication & Remedy:  Personally I think this would depend on the situation. 

Mold was present and mold remediation was required.

As an investor, you have the right to a contractual remedy (that you purchased in your investment) that protects your principal.

The concerns about the age and condition of the building are unfounded as they are easily remediated with minimal time or capital.The issue about parking is also strange given that it is an urban neighborhood and it is quite common.

The neighbors told me that a remediation outfit in haz-mat suits spent 3 days pulling stuff out of this place.

Pursue legal remedy against the previous owner and agent that misrepresented the property as a legal 3 family in advertisements and in person. 

The current owner had told him the lead was taken care of, but I know for a fact after inspecting, there was definitely some lead remediation to be done.

It has only happened once, and through amazing luck, they turned out to be the nicest drug dealers ever and helped pay to remediate the special venting they had constructed through my roof without permission.