In the earliest picture the sporran was much more of a traditional Scrip, a money bag held on the belt, worn even with Saxon clothing, before pockets in trousers became common.

The miltary picture are not relevant because the British military almost always issue the same Black boots and shoes to all personnel. I was only issued brown boots once, to be worn with overalls at your working place, they didn't have to be highly polished just clean and looked after. Woe betide you wandering off still with them on..

As for the rest, it's a matter of choice, I wear black boots and shoes whether in Saxon clothing or Kilted. The only exception is Blue Deck shoes. As to sporron mine are also black, simply because I haven't found a brown one I like, I can justify spending the money on..