I would definately not reuse any substrate nor bother with what is refered to as "live sand" out of a bag. Just replace with new washed substrate. If you have enough live rock I wouldn't save any more water than you need to transport everything in, water is not cycled. And as mentioned above if possible have premixed adjusted salt water at the new place ahead of time if possible, and a temporary tank would be a great idea while you get reset up.
Best of luck