Sure, they can file that for you, if they can show there are insufficient U.S. workers for the position and that it is seasonal.

They will probably let you into the building but I suggest updating the drivers license, as required by law.

It depends on what application you filed and where. Check with www.uscis.gov for processing times.

Put the date your next semester begins. Obviously you are not likely to get that date.

If you were granted a change of status to H1b, you can port to a new employer if that employer files an H1b application for you.

A lawful permanent resident can apply for a reentry permit, which is good for up to two years.

You could certainly request it, but very likely your circumstances are no different than any other K1 adjustment applicant's.

You can continue to maintain your OPT status. You are not required to notify your employer to use a different EAD card as proof of eligibility to...

A permanent resident of the U.S. can work in the U.S. for himself, as an employee, or as an independent contractor.

There is no fee, so CIS either made a mistake or your I-765 got separated from the applications.