You might want to set parameters around communication with your ex (can't recall if he's prone to harassing emails/phone calls/texts), saying that communication will be restricted to matters directly involving the children. That doesn't mean he won't still overcommunicate but it means you are on better ground to just ignore him if he does.
Other possibilities:
-Do you want to be notified by ex if he will be attending kid events (sports, school functions, etc)?
-How about contact between the kids and any members of his extended family?
-How about contact between ex and any members of your family?
-How about communication of information about kids to ex - do you want to commit that you'll send him copies of all school and medical reports (might be a nice gesture to throw in, after you've set strict rules around how much he can actually see the kids)?