first off, I feel for you in terms of not sleeping. I have a 23 month old and have had plenty of sleepless nights since she was born. I hope you can get some rest today. Does your son nap?
Your son sounds as though he would be a wonderful playmate for my DD. She loves dinosaurs, space, science, etc. We went to this dinosaur show with huge robotic dinosaurs and she went around telling people the names of each one and some details. People were shocked that she could say their names LOL
Sometimes she does get very concerned about certain things and it does sink in very deep. She will talk about death, floods, blindness, and so on and I worry that she is leaving the obliviousness of childhood too soon. I do not openly bring up these topics but she just picks up on them from various sources (she never sees TV that isn't for children so it isn't from there).
My DD is very outgoing, bossy, talkative and enthusiastic but is has been hard to find good playmates for her. She can connect with kids of all ages, and have a good time, but she has never met someone she can really talk to and play makebelieve with on her level. She isn't very tall so even though she might do well with a 6 year old, we don't seem to meet very many. She met a 5.5 year old today that she had fun with for awhile. That's great that you son has a little buddy even if they have different levels of communication.