Gosh many a time did i have to deal with Q1.
Firstly check out what seats around are vacant. If enough seats are available go into the flight deck or use intercom and ask the Captain if pax are able to move as the family has been split. show him on the trim where you want them to sit and then if it all works out re centre of gravity and max take off weight blah blah blah he should then, if he is nice let you move pax. Very important though that you don't move kids into the emergency exits though. If for some reason you arn't able to move them always explain to the passenger the reason. That way they won't thing you are being nasty.
Q2
if it is tech crew.. go in and tell them to grow up and sort their problems out in a civilised manner or they will not get anymore coffee or cabin crew. tell them to be more professional and deal with it on the ground.
I have dealt with both these probs many a times and believe you me they are very common. take care and enjoy....