Weiman Stainless Steel Cleaner Aero - 340 G

I have always cleaned stainless steel horizontally with the grain. Your video shows the lady doing that in a circular motion. Which way is correct ?

How long can this product be used?

In the description, it says “polish aerosol, birthday cake, 12oz”. what does birthday cake have to do with anything?

Is the quantity, 2 cans?