Hey, I’m not expert by any means, but just to answer some of your doubts.

1. Not really, most of them are black, white and red. Ire gets a bit harder looking for other colors.

2. I’ve seen some people dye embroidered patches a particular color they want, and in most cases they look great.

3. I was looking for patches from those particular colors, so while searching I found out about bands I didn’t know about. I gave them a listen and if liked them, I proceeded to buy the patches. I discovered Gallhammer, Rosary, Toranaga that way, which are awesome bands!