On current firmware it's a plain, production-ready operation — no special mode, jumper, or factory tooling . You stage the new address, arm the change, and commit it (a two-phase, magic-armed sequence...

Yes — that's a core feature. Modules share one I²C bus and differ only by address. Add circuits by adding modules on the same two wires, behind one host — no extra microcontroller, no serial-port jugg...