Can I file my 2015 separately from my estranged husband?

Yes, you can file separately and it might be a good idea to process your return MFS

Can my ex husband legally get a roommate?

Don't call the police. Call your attorney to interpret your MSA and if he is in violation, advise ex before rushing into any legal action .

Can an officer be held responsible for a Labor Relation case if the corporation dissolved

Yes, there is a possibility that you could be held at least partially liable, depending on the facts.

Is this crime, that living in Florida for 2 years, and not having Florida license ? What Rule applies here ?

If someone is employed or has children in school in Fl, they should have a FL DL under Fl traffic laws. I don't see much relevance to a family law...

Just ask him or his attorney first.

Is it possible to file a claim for damages due to preparer misconduct? Can I do anything besides file a complaint with the IRS?

Withholding miscalcutions or not, if you owe the tax, you owe the tax. Maybe the EA or another tax pro could reduce any penalties that may have...

How could we protect ourselves my daughter and I? What should I do?

The police were correct. You need to take legal action ASAP. Best to have an attorney represent you.

Enforcing child support

No, you normally just can't 'write' a Judge and ask for something. Legal proceedings should be followed, including notice to the other party....

Is Under the Table Work ever legal?

No, if it were legal it wouldn't be 'under the table'

How do I report this error to the IRS?

Respond in writing and by phone to the address and phone number on the notice.