The QR Code is the bridge between your physical shop and your online catalogue. The customer points the camera and lands straight in your store.
Done: it's your file, to print wherever you like.
On the same black bar:
To send by message, the link beats the QR Code. The QR is for the physical world.
Don't print it too small. About 3 cm per side is the minimum for a phone to read it up close. On a sign read from a distance, go much bigger.
Leave a white margin around it. A QR Code running to the edge of the sticker tends to fail.
Dark code, light background. A light code on a dark background may not be read by some phones.
Test before ordering a hundred. Print one, scan it with two or three different phones, and only then order the rest.
Say what it is. A bare QR Code on a wall invites nobody. Write underneath: "Point your camera to see our catalogue".
No. It holds your catalogue's address inside itself — no link shortener, no middleman server. As long as the address stays the same, the code works.
But: if you set up a custom domain after printing, generate a new QR Code. The old one points to the previous address.
The link comes out in whatever language your app is set to. If you serve customers in another language and want a QR for them, switch the app's language before generating it.