This is appropriate as an explanation.

It can take 30 days or more to receive your physical GC.

Yes it is okay to use this as your parents mailing address.

Yes you may have two joint sponsors.

Best to consult with an attorney to explore your options.

Best to have another opinion with an attorney.

You may need to refile for the I-130. Consult with an attorney to explore your options.

It is recommended to bring an attorney to interview given information provided.

No while not required you may bring along to interview.

Yes you may marry now and file for the I130.