I have some questions about Kilts and such

Should all the leather in the outfit be of the same color? Like kilt straps, chain straps on sporran chain, and shoes?

Should a Fly Plaid be the same weight as the kilt? I will have to have what I want woven.

What sort of Head gear is best worn with a Prince Charlie, if any?

Is it proper for the stone in a plaid broach to be of similar colors, like ancient Lamont with emerald stone or is it better for them to be contrasting?

Thanks