Adjustment applicant would probably work just fine.

You are required to stay in the U.S. while your I-485 is pending. If you depart, generally, you will be abandoning that application.

If you are a conditional resident, file to remove condition. If not, you can file to replace the expiring green card. You do not have to file for...

They will find out about your overstay. They have records of departures.

If you were allowed to port to a new employer you can port again to another new employer.

That is a question for a Canadian immigration lawyer. But in all likelihood, since you are simply changing planes and not entering Canada at all,...

If you previously overstayed, expect them to find out.

Since he needs to take his biometrics now, and that costs money, it seems to me CIS can require you to pay that.

Very likely they will issue you a Notice to Appear at the Immigration Court. You should meet with an attorney to discuss whether you are eligible...

Perhaps you qualified for recapturing your earlier priority date from your original green card. If you believe it is a mistake, just wait to file...