Well, first and foremost make sure he's giving you about 8 wet diapers a day. As for BMs, my son pooped every.single.time he ate, but I've heard that other babies may only poop once a week. Of course, that's more likely with formula fed babies, but if he doesn't seem uncomfortable, I would try not to worry too much. You can always call the doctor and see at what point they would want you to intervene. If he is dehydrated, that could make him constipated. His wet diapers should be fairly clear and colorless, so that would concern me some. I would really try to make sure he's nursing about every 2 hours or so if he's going that long at night without nursing.
How often and for how long has he been nursing? Just push that until his urine is clear again and you're getting enough wet diapers.
As for how long he's sleeping, as long as he's eating during the day and giving you wet and poopy diapers, I wouldn't worry about it. He may be going through a growth spurt and need the extra sleep. Or maybe he's working on a new skill that's tiring him out. You might want to consider pumping before you go to bed to help maintain your supply. Going that long without nursing could eventually cause it to decrease.
And as with anything, if you're concerned, call your doctor! That's what they're there for! Good luck, and congratulations on the newest addition!