A non-attorney can prepare documents so long as they report it on the form.
It is unclear from your posting whether you initially believed the filer was a lawyer. This is considered unauthorized practice of law and is a national concern [http://www.stopnotariofraud.org/]. There should be ways in there to get help if that is the case.
New Jersey is one of, if not the only, state in the country that has a "whistleblower" statute that includes private employees (the Conscientious Employee Protection Act, or "CEPA"). Depending on the facts of your case, if you reported conduct which you reasonably believed was "illicit" or "illegal," then were retaliated against, you may have a cause-of-action. I would review all the facts with an experienced employment attorney to decide whether it is in your best interest to proceed legally.
You probably do not wish to renew her visa, unless you meant she came with a green card that expired. If not, you should petition for her green card on the basis of her marriage to a U.S. citizen, assuming she is eligible. I would suggest consulting with an immigration attorney to determine whether that would be an option.
It would depend on what exactly you were convicted of and/or plead guilty to. I agree with my colleagues that the best course of action would be to obtain certificates of disposition and have an immigration attorney review the relevant criminal code sections to advise you of their effect, if any.
Yes and yes. You are generally allowed to bring an immigration attorney with you to your interview. An attorney may make certain comments and provide documentation to the officer in some situations. Different offices handle this differently, but the general rule is that immigrants are allowed to have counsel at these interviews.
While the final rules have not been finalized, I agree with my colleagues that your last entry after age 16 may make you ineligible (also, there are education requirements proposed that you likely would not satisfy). Regardless, consult with an immigration attorney to discuss in detail your eligibility under the current proposal and your possible eligibility once the rule is finalized.
Fiance visa is an option, but if you want to get married in Ecuador there is no reason to waste time and money on fiance visa unless you need her to come to the United States right away. You can save some time by filing for the green card after you get married, but know that she will need to remain in Ecuador until it gets approved. Your best bet is always to have an immigration attorney advise you about the process and help you file all applications correctly to avoid unnecessary delays.