Suggestion and question involving guild icons

When you join a guild you get an icon next to your name or the entire guild name in brackets under your name if you turn that option on. My suggestion is to display the full name by default. Yes, this takes up more screen real estate, but that is where my question comes in. What the heck do those icons mean? I see the same icon on every guild, though sometimes the colors are different. I made a guild on another character and thought maybe there was a way to customize my guild icon but I didn't see it anywhere. In that case, the icon doesn't show your guild pride, it just says "I'm in a guild." So please:

1) Tell us how those icons work
2) Make it default to show the full guild name