1. Gold membership should be good through the end of the month stated (Nov 30th in your case.)

2. If you score 50,000 miles before Nov 30th, you should be okay and have no gaps in your Gold Status. If you don't achieve 50,000 until December, you'll lose your status for that short period after Nov 30th until you achieve 50,000 and the system updates your status.

3. You should see a 5,000 mile bonus to your account when your renewed Gold status kicks in, and should have a Gold upgrade waiting for you.