Oops, I already submitted, but fortunately did everything you said except for attaching the representation form. It did not ask me to attach that form. I hope it's not needed or at least they ask me to send it over.Yes as a PR you can order on behalf of anyone, including your wife. I ordered it for my wife, my brother, and also for my parents visit visa. As part of the application, you have to attach a form (given there) where that person appoints you as their representative to order on their behalf. It has to be signed in blue ink. Order it under access to info act, costs 5 dollars. You can ask me if you get stuck somewhere.
Hope it helps