The order id will be unique on the shop so you can safely develop under that assumption. You'll have the shop id at hand as well so you should generally use that to help isolate any data your gathering from multiple shops.
I jump on these forums to help and share some insights. Not looking to be hired, and not looking for work.
Don't hand out staff invites or give admin password to forum members unless absolutely needed. In most cases the help you need can be handled without that.