one of the best things you can do is just LET your son have a full spectrum of emotions. now, there needs to be limits - he can't tackle the refrigerator, or beat the stuffing out of a sibling - but he does need to know it's OK to have feelings and to express them. family counseling or a child therapist could be invaluable at this time.
it's going to be a turbulent time - changing houses. even in the BEST of circumstances there is unrest. and where IS the toilet paper????
you are doing well with the transition, focused on creating a new safe place of sanity and respite. it will take time for everyone to adjust.