Is 10AWG copper wire sufficient

I think you would be prudent to star with garden-variety 10 or 12 gauge cable, such as the stuff available from Blue Jeans Cable. Listen to it for a year and then you'll have a good point of reference as to whether you hear any meaningful improvements from something more expensive. In short, plain wire is fine.

I would think something like 16 gauge would be sufficient. Having multiple strands that would sum up to 10 gauge is quite different from a single strand of 10 gauge.

All the best,
Nonoise

Never understood the whole AWG system. Why not use wire diameter or wire surface area in mm or mm2? No one outside the US knows what AWG is.