Cut yourself out.

The model that runs well in a browser under a licence we can use commercially is a human matting model. On a person it is excellent, including fine hair edges. On a pet, a product or an object it produces a ragged, unreliable cutout, so rather than let you waste time on those we say up front what it is good at. The Yaps desktop app uses a general-purpose model that handles any subject.

No. The model is downloaded to your browser once and the photo is read straight off your disk. Nothing is sent to a server, which is also why there is no queue and no file limit.

A PNG with a transparent background at the original resolution, or the same cutout placed on a solid colour if you pick one. Both download straight to your machine.

The cutout model is about 7MB and downloads the first time you use it. Your browser caches it, so later photos start immediately and work offline.

Usually, yes. It mattes people rather than one specific person, so several figures in a frame are generally kept together. Very small or heavily overlapping figures are less reliable.