Good luck getting #1 out of your bed before baby gets here! We were in your same boat, a few months ago, and it didn't happen. We had both boys in our bed for a few months and thank goodness, the new baby loves his crib and has been sleeping in it for about a month now. We are still trying to get the 3yo out of our bed, so now we are bribing him with going to an ammusement park. Bribery worked with potty taining. :)
I have to admit though, the times when he is in his own bed, we do miss him, he's very snuggly. We really enjoy co-sleeping and if we had a gigantic bed, we would all sleep in the same bed!
As far as the baby waking up the toddler, our 3yo didn't wake up much when the baby cried and when he did wake up, since he was in our bed, one of us would just cuddle him right back to sleep.
We also decided to have the boys share a room hopeing our 3yo would be excited about having his baby brother in his room, in hopes that, that would get him in his own bed. Our son is too smart and that isn't working either, sigh... I think the ammusement park bribe is going to work though, since that is all he was talking about yesterday. :)
Someone gave me some good advice to put a TV and DVD player in his room, so he can lay in bed and watch a movie as he falls asleep(that's all he can watch on this TV) and that does keep him in there throughout the movie, but he comes into our room when it's over. I'm wondering, if we would have done this when he was two, if he would have just drifted off to sleep better. Good luck to you, whatever you decide!