Depends on the distance between your Arc and the Amp controlling your surround speakers. Normally they connect across a hidden 5Ghz connection, my second choice would be to wire them both to the router, due to the small additional networking delay.
Yes, your TV would communicate volume commands to the Arc across CEC (ARC) via the HDMI connection. However, the TV’s remote control will not work when streaming music, you’ll need to use a controller for that.
