Hold on and take a deep breath! It will all be ok. It will take a bit but I promise they will adjust and be ok. I haven't moved with my whole crew but we did move with Sammy. He was terrified of all the things being taken from the house. Everything familiar to him was going out the door and he had no place to hide. It was awful for him and he was so very happy when we loaded him into the carrier and took him with us. I really think the poor guy thought we would leave him! Your idea of boarding them is the best way you could handle that. It is very fightening to be locked in a room and noise and strangers in their home. I think you have a wonderful idea by taking them to PetSmart.
This is just my opinion and what I would do now that I have more cats. I would take one room and make sure everything is set up there. Put their favorite beds, food dishes, and litter box there. When you bring them home I would keep them in that room for an over night until they calm down. When we moved hubby carried Sammy through each room and let him sniff all of the familiar things. He let him sniff the beds, the kitchen table, while showing him the way around the house. Sammy adjusted very quickly once he realized these were all his usual things just a different house.
It will take the scaredy cat a little while but I promise he will be ok. They will still have their own stuff and their very special and loving meowmie to help them adjust.
Good luck and I'm sure you will have good news to report in no time.

Congratulations on your new home by the way!