Anyone that has that information available to YOU better be the borrower or, by authorization from the borrower, the lender directly.

And no, the police have no authority here.....it would be an eviction/ejectment proceeding if it goes that far.

., couple of caveats and structures for you to examine:If the seller transfers the property into an inter-vivos revocable trust, and names you as trustee and your entity (llc, corp, etc) as beneficiary, you will, as trustee, be able to notify the lender, insurance company and taxing authority of the change of address.  

I arrange tours of the property and talk to tenants about their move in requirements and ability to pay upfront costs.We offer applicants that are interested in moving forward after the showing the option of taking the honestrenter.com quiz or authorizing the transunion smartmove credit/background report.

You can either sign a POA as @Jennifer Petrillo suggested or you can sign the closing documents (deed, etc.) along with an authorization form (a very limited POA) and the attorney can sign the closing disclosure document at closing. 

Does the new owner have to honor the current lease agreement with the Chicago Housing Authority?

If you google "HUD-VASH your local city/county name," you will probably find the local housing authority that administers it (local to me it's the same people that do sec 8).

I would reach out to the local authority having jurisdiction.

"Any hydrostatic testing must be separately authorized by Seller in writing"The test failed and now they are using this as leverage (obviously).

If your agreement does not give them authority to set the rental rate, you may have an argument to pursue them for damages, assuming they set rent too low.