My advice would be to use a pack-n-play or a "co-sleeper" bed. The co-sleeper bed is a lot like a pack-n-play but it sits higher up so the baby is at your level next to your bed. I am not sure if it is designed for kids who are rolling over, so you may want to check with other moms who have used one. The side that connects to your bed is "open" and the other 3 sides are like that of the pack-n-play.
As for the crying in his sleep, if he is still sleeping when he is doing it, it may be night terrors. My son also gets them (he is 17 months). I would ask your doc though becuase 7 months sounds a bit young to be getting night terrors.
If he is waking up in the middle of the night crying, it could be he is hungry (if going through a growth spurt), teething (very likely at his age), or an ear infection.
If you think he is teething, I would try giving him Tylenol or Ibuprofen right before you put him down at night and see if that helps. My son had 4 teeth coming in at 7 months and we had about a week or so of nights like that. Then he would be fine for a few weeks and it would happen again. It seemed 4 days or so after the crying started we would notice one or more teeth trying to pop just under the surface. Your baby can experience pain well before you see the tooth.
I hope this helps,
M.