Yes, but my experience tells me that you'll interact (on a level where timezones matter) much more with people in your country than in others - and this has nothing to do with small states vs big provinces, I don't know enough about Canada if every big company has offices in Vancouver an Toronto (or Ottawa, Montreal) that work closely together.
Not really. That might change due to what is going on in the world, which is now seeing provinces having to become serious about expanding into new markets, but in the past sharing timezones with the USA has been much more important for the sake of industry. Again, things are now starting to change, but historically the provinces haven't even had free trade between themselves — despite having free trade agreements with the USA. That's how much they have worked together.
Sadly that is not really true in Canada. Most companies in Canada only really work with a small group of close provinces.
BC/Alberta
Sackatchewan/Manitoba
Ontario/Quebec
Quebec/New Brunswick
Nova Scotia/PEI/NFLD/New Brunswick
etc
The big companies have offices in each, but they'll usually break them down even further into eastern, central, western regions. And they'll largely never talk to eachother.