[Kasey]

My son was younger ( 5 1/2 months) when he came home. Basically I slept in his room with him in the beginning, we always rocked him to sleep and put him in his crib at night. During the day, I slept with him for nap #1 and he slept in his crib for nap#2. We always put him to sleep in his crib at night, but if cried we immediately picked him up, if he didn't go right back down to sleep he came in bed with us or with me in the twin bed in his room.
Our IA doc also encouraged co-sleeping. I also am a light sleeper, so I was awake quickly, DH sleeps like a log.
This worked well for us, we didn't plan it, just figured it out was we went along and took our cues from Alek, the napping together I did plan.
Maybe you could sleep in their room with them and be there as soon as they need you (I agree 4 in a full size bed is tight, we have 3 of us in a king and sometimes I feel smushed!).
I would say try some different things and you will figure out what works best for the kids and you!
Good luck!