Twas getting lonely in here.
It must have felt strange leaving O for the first time, but it is great that you have family support over there. You sound like you are getting on with building your life and O is obviously loving it.
My O can't sit unaided although he wants to. We pad out the highchair otherwise he tilts.
Yes to the bum lifting, O loves that! I think part of the reason for his crap sleep lately is that he is really discovering his body and what he can do and he likes to practice at night 
Not sure how tonight will go, but he has had an active day and two poos. Hasn't fed much though. There are no patterns to his nights so god knows.