You can obtain your records by filing a FOIA request.

While not required it could be helpful depending on the specifics of your case. Consult with an attorney for guidance.

No only the I485 and supporting forms and documents is required after marriage.

You can do either - send with application or bring at time of interview.

As long as you are in the US you should not have a problem.

Yes that is what the notice indicates.

There is no limit to this issuance of PFD.

That should be okay to proceed with given intention.

Contact the cruise to inquire about travel requirements between countries.

Yes you should be able to do so despite status.