Is the Gucci YA142303 a mechanical or quartz watch?

It is a quartz watch. A battery-powered quartz movement keeps time accurately with no winding, which is the main practical difference from mechanical rivals.

Is it suitable for swimming or showering?

Treat it as a daily dress watch, not a dive watch. Gucci's fashion watches are generally rated for light water contact at most, so take it off for swimming and showers.

How does it compare with a mechanical watch at a similar level?

The Gucci wins on convenience and brand recognition. A mechanical watch from an established watchmaker offers more horological interest and often better long-term value, but needs winding and servicing.

What should I expect in the box?

Expect the watch on its stainless steel bracelet with Gucci packaging and paperwork. Confirm the exact contents with the seller, since bundles vary.

Can the bracelet be resized?

A steel link bracelet can usually be adjusted by removing links, but this needs a jeweler or watchmaker with the right tools. Ask about sizing before you buy.