E.B.
I dont have rock solid advice. I have been a co-sleeper. I can appreciate where you are coming from though. You may just have to stay ahead of the game. Instead of feeding on demand, you may need to get up half hour before baby will wake. this going to take some trial and error. sadly your older one may be screwed up, schedule wise for a bit. Once you have a pattern down with new baby though it will become easier!!
Good luck and congrats to you and the family!!