Gates 200 to 299 is the so called "East Beach" terminal. On arrival you will be immediately guided to a bus that will take you to the main terminal where from there on the process is the same as if you had arrived directly at the main terminal. There is a coffee shop in the satellite terminal, and I think a small newstand but you won't be allowed to access them on arrival as they escort arriving passengers straight to the bus.

You will have to go through an abbreviated Canada customs check then you will be allowed into the airside departure area for international flights where there are shops.

On the way back it's the same deal, you'll be funnelled to the customs check without any opportunity to shop, you do have to do both, go through the abbreviated Canadian check then on to the US customs hall. Once you have re-cleared security you can access the shops before getting on the bus to the East Beach.