Unless something's changed in the past few years (like how YYC basically tore down the wall demarcating their "international" terminal), it's not very easy at all to exit the international gates at YVR. I've only ever done it once on a ticket that I had to:
(1) cancel check-in,
(2) get the MLL lady to offload me from the flight,
(3) get her colleague to call CBSA so that I could re-enter Canada,
(3a) that colleague is satisfied that I'm truly not flying today and asking me why,
(4) CBSA is satisfied I didn't buy anything new at the gates since I technically don't have a duty-free exemption, but they have to do the entire declaration/cancel ex-Canada record over the radio since I'm not at the typical border facility,
(5) re-enter landside via some service hallway

And all this was for travel originating from Canada, it was very inconvenient. I think you'll have a much harder time trying to stay on your flight but entering Canada from the part of the airport that isn't designed for it simply because you wanted breakfast...sorry

It'll be much easier for your to enter Canada the regular way and forget about the international terminal until it's time for you to return and enjoy it. There's decent brunch and dim sum within minutes of the airport via public transport, you'd be missing out at the MLL anyway

Yes there's baggage storage