I am AA Gold Elite and have booked JetBlue in the past with my AA # and have received the EMS seat upgrade. Now looking at a trip BOS - SEA with an AA flight on B6 metal. Two questions:

1. If I book through AA I can only book using Main Cabin, but if I book on JetBlue I can book Blue Basic at a lower fare. Will it matter as I am already Gold status on AA so I will get free checked bags and EMS if available 24 hours prior to departure.

2. If it is an AA numbered flight but B6 metal, can I use my AA companion cert at the AA price?

Thanks in advance.