Yes, Cycles and EEVEE. The grime and the plastic look best in Cycles.

Yes. They are driven by the scene time, so they buzz when you play or render an animation. Some sit still on the rubbish.

Yes. It scans whatever is visible (or only the selected objects) and finds desks, shelves, seats, beds, window sills and the floor by itself. Objects named desk, shelf, bed, chair... are recognised even better. Real-world size (metres) works best.

It adds its own objects in a "Lived-In" collection and slips a grime layer in front of your materials. Clean Up deletes only what Lived-In added and plugs every material back exactly as it was. Nothing of yours is moved or deleted.