Can a employer terminate a group of employees one month after making them to sing a reasonable assurance letter for employment?

Without seeing the entire document, there is no way to offer an opinion on a document.

You can always sue, and try to subpoena the document. But defamation cases are tough. Do you know exactly what he/she said?

Can a company be held accountable for knowingly allowing a wanted fugative to work and live at their buisness?

I'm not sure what you want to do. From your post, you have no damages.

Can I put down that I had no felony on an application for a position if it was dismissed?

Do not lie on an application. That is a valid reason to terminate, no matter how good a candidate or employee you are.

How long after disparagement can person get sued (employment separation agreement)

without reading the entire agreement, it's impossible to offer to offer a fair answer interpreting the document. You can google disparagement,...

Do I have a case if I worked free overtime a little over 10 years ago because I didn't know any better?

You are beyond the time to file. Sorry.

If company doesn't pay severance at firing, would I have a case to get money back?

There is no statutory right to severance. It all depends on the policy terms.

Can I file a medical malpractice suit on ruptured silicone implants?

If you were part of a class action, you likely cannot bring a separate action.

Can my employer pay me less than they promised me?

Even if you would be able to prove a breach, you have about $150 in damages.

Can I sue

Discrimination has to be a protected class (age, sex, race, etc.) to be actionable. An investigation does not have to be perfect - just in good...