Some are required by law, so check on those requirements and get any documents you'll need.Good luck!

Using a document search online I found a recorded "Subordinate Mortgage" from the Secretary of HUD on one of the properties that I had planned to bid on. 

HOA manager here... if there truly is nothing in the covenants or other documents allowing them access then you have a case for making their lives miserable if they enter your premises without permission.

@Bobby Walters The Chattanooga Housing Authority (CHA) website has a very nice collection of documents that are publicly accessible, including an Excel spreadsheet showing the Small Area Fair Marker Rent (SAFMR) by zip code.

Anyone can have a really good website these days for less than 100 bucks and with some effort, anyone can also build a legit looking FB page.is there any document that I can ask them to show proof of their credibility?

You usually have a feasibility period or due diligence period where all of these documents are disclosed.

The judge also said we need to file with the other person in the room on the eviction documentation even though we only have one person registered as a guest.  

The court clerks, and judges were familiar with me and my documents were in order so usually simple outcome. 

It performs thorough background and credit check by scouring court records and documents 

Investors are not permitted(system does not allow investor bids during this period) to bid during the Exclusive period When you purchase a HUD as an owner occupant, you sign a document that you will occupy for at least one year