Powered, as in active? No, those are connected internally. Cabling is then between the internal amp and a preamplifier, which is line level.

I would point you to the overwhelming lack of any reported incidents of speakers or amplifiers catching fire because the wires were too thin. This is simply fiction.

Coat hangers are generally much wider than any speaker wire, and the metal used makes little to no difference to the sound or the load. It is of no importance, you can do this safely.

As I’ve said, there are a few scenarios where you could run into problems, but these are very much outside of home hifi.