It depends on what the store needs most. It's looking to fill the ranks for the busiest days. Most areas have high business on the weekends, ie. Friday, Saturday, and Sunday. The SM or hiring manager will be the one making the decision.
Best of luck!

Just say you're open. My manager gives me Sundays off since I'm willing to work Friday and Saturday.

Completely depends on the needs on the store. I would definitely recommend trying to have some kind of availability over the weekend, even if it’s just a 5 hour slot Saturday morning or something

It's completely up to your manager. If your availability doesn't match the needs of the store then you won't get hired.

It depends on the store. When I applied, they said that “weekend availability” was required, but it turned out just fine that I could work Saturdays but never Sundays.