Normal
My son has high functioning autism and what you described sounds a lot like him (only that your kid seems to do better overall, my son rarely appears typical) We moved across country when my son was 7 and it took him a good 3 month to find his footing again after we moved into our permanent house. He had a lot of tantrum and a lot of really out-of-it behaviors. School got pretty bad for a while too. This kind of change really deregulates kids on the spectrum. Keep his schedule as consistent as possible, give him advance warning for changes and don't expect him to do well when the unexpected happens. As far as what you do mid tantrum -nothing other than minimize sensory input. Don't talk too much in a meltdown, keep yourself even and just give short supportive directives. You can talk about what happened later. Mid tantrum it will only push his anxiety higher. It looks like aggression but it comes from anxiety. At this time he needs structure and understanding, consequences (as in punishment) are not helpful for these kind of tantrums. To me he sounds like a good kid on the spectrum who struggles while his life is out of whack. It does not sound like bipolar to me. Of course if there is a history of bipolar in the family you would have to keep that in mind.