We have a queen and bedshared with our 2yo dd for about a year and a half until I HAD to nightwean for sanity. It was really not a problem at all to transition her to her crib in our room and then her own room a few months later. I was so worried about it, but it was fine.
I LOVE the idea of kicking dh out of the bed for a few weeks! :-) That is genius. Having 3 of us in a queen for so long caused a lot of stress in my marriage, because it's a tight squeeze. Dh wants to snuggle and doesn't understand that nursing moms snuggle for most of the day, every day, and really don't want to be sandwiched in between 2 bodies in bed! Dh did end up sleeping downstairs for a few months while we were nightweaning and it was really nice to be able to stretch out and not be bothered by his movement and noises all night long. I may have to think about this some more...
We're planning to side car a crib this time to essentially use as an extension of our bed. I didn't learn to nurse while lying down for a few months with dd, but plan to do it right away this time. If I can figure out how to nurse while the baby is on the firm crib mattress, I will feel safer because our mattress is a little squishy. I slept so lightly with dd that I don't think it will ever be a danger to have the new baby nursing in bed with me, but I would sleep better if the mattress was harder!
I wanted to jump in the discussion about the Arm's Reach cosleeper. We had one for dd and used it for about 2 days. We have a mini one, and maybe it's different than the regular sized one, but you can't nurse the baby in the mini cosleeper. The cosleeper mattress is about 4 inches lower than the lowest side of the frame. We had it set up so that the frame was even with our mattress, so the cosleeper mattress was lower than our mattress.It is essentially a bassinet that attaches flush to the bed. I had some swelling from the birth and couldn't reach over to get dd in or out and it was actually harder on my back than getting a baby out of a bassinet would have been because it was attached to the bed so I couldn't put my feet on the floor before I picked her up. I felt like it was a lot of hype for nothing.