The answers to your questions likely depend on with whom you are doing business, and also upon what questions you ask of them.
I have a broker with whom I have done business for several years. My original hardware vendor no longer deals in Canadian satellite systems, but they recommended someone from whom I could purchase an up-to-date receiver. I asked nicely if that new hardware vendor would work with my existing broker to pre-activate the new receiver before shipment, and they agreed. So the box arrived ready-to-go. My broker charged me $10, as expected, for the activation service.
But unless you ask, your box will likely arrive unactivated, and you will need to then call your broker to get activated.
If your broker and hardware source are one-and-the-same, it
might arrive activated, but I'm betting you will have to ask if you want it pre-activated, or call them once it arrives at your home.
Also, keep in mind that the minute you activate your new receiver, you will likely incur a multiple receiver charge of about $6/mo by Shaw. If you're going to take your old receiver out of service, you should so-state to your vendor/broker. I'm not sure if you incur this multiple receiver change if your de-activate the old at the same time as you active the new.
Also, if KuSat provided you a PO address, does that eliminate the need to use a broker in Canada for service in the US?
I'm not sure about KuSat policies, but normally a PO address is not sufficient to use as a "service address" for the purpose of establishing a Shaw account. I believe the "service address" needs be an actual property address.