T-Mobile pre-paid data plans/data passes, FWIW, work great in Canada. US$10 for 1gb for a week, roams onto Telus/Bell/SaskTel, and will keep you covered basically anywhere there's actually service along the Canadian route.
Do not count on any VIA-sponsored WiFi being available in the en-route stations. It might work when there's nobody there, but when the train pulls in and everyone has the same idea to check their email, trust me, its very frustrating.
Luggage is stored in a baggage car at the front of the train, with the exception of a small carry-on bag. You will not have access to the baggage in the baggage car short of a pretty significant calamity (ie: you messed up bad and left your insulin in there), so plan accordingly.