We just moved to Malta from 10 years in the US - I'm British, wife is American and kids are dual: 13 yo daughter and 8 yo son. Our daughter was VERY apprehensive about the move for the same obvious reasons, but now she's been here for a few weeks (she started at San Anton school on 4th Jan) she's made some Maltese friends and has already been on her first Paceville trip! So, I echo the sentiments about the local teens being welcoming, at least in our experience...the school paired our daughter up with a classmate to help the transition, not someone picked at random, but someone that wanted to do it and they are now firm friends, so our thanks to the school for that!
Tim