Advice on moving baby boy into his own room?

My son is almost 4 months old and we have decided that after the 1st of the year we will be moving him into his own room. He has always slept in a playpen right directly next to my bed since th day he came home from the hospital (at just 24 hours old). I have the Mommy Worries about it, but we have decided to go ahead and do it. With our daughter we all shared a room until she was 1 year old because we were living with other people until we got our own place. So we didn't have a choice. Thank goodness the transition was extremely smooth with no issues. This time around he is much more attached then she was. He is a BIG TIME Mommy's BOY. I went out and bough a camera which hooks up to our flatscreen in our bedroom. So we can see him absolutely perfectly and can leave the TV on all night until we feel comfortable. Also another worry I have is the ONLY way he sleeps is on his belly. He has from day 1 and refuses and throws a fit if you lay him on his back. Also, he has just stared on baby foods & cereal. So will that affect him at all at night when sleeping? I'm scared he'll spit up, and cause its so thick, he'll choke. Anyway...how can I make this transition best for the BOTH OF US?