Since it is a campaign setting, you can't just up and change your list unless you restart. Changing his list could take a grueling amount of games to grind out the changes but then if you aren't having fun, why bother? We started a RitR campaign and IMMEDIATELY ran into that "no fun" problem of players bringing the biggest ships they could. We played two rounds and restarted the whole campaign with a house rule of no large bases allowed. It mades things a lot more fun for everyone; the fleet builds were more creative and a lot of our otherwise under used ships hit the table.

Consider that if you wait until you finally find out if they are changing Gunnery Teams that the SSD may no longer be available by then.

If you're playing friendly "casual" games there's nothing wrong with you both using the same damage deck. The starter set, meant for two players, comes with only one damage deck. It's not like there's much tournament action going on at the moment and even if there was I am sure you could ask around beforehand and someone in your local community would have a spare your friend could borrow.