As long as you want. I had a XS Max that I bought from AT&t several years ago. I kept it in the box for a full year before I opened it. I registered it and the warranty started on the day I registered it, not the day I bought it from AT&t

I funny think you will lose the card. It will move to another bank.

I get downvoted every time I say this, but in the 16 years I’ve owned Apple devices, I have never paid for AppleCare, and I have never needed it. I have had numerous iPhones, pods iPads, and Apple watches, and I have never needed it for any single one of them. AppleCare is designed to make Apple more money.

Longer battery life

I’ve had my watch for a month and it’s never down a temperature reading.

It’s a phone. Who the F cares.