BedWars plugin planned

Hey. I'll start to create a bedwars plugin.
but theres one problem i have:
Teams.
Any idea how i can make players join them?
I had the idea to click a sign or execute a command, open a fake inventory and when selecting a wool color, you'll be added to the team.

Should i use mapped arrays.. or $team_blue = array() && $team_yellow = array() etc?
Or any better idea?

And what about The villager trades?

I just got my VillagerTrade plugin working, but i don't think about using all of that.

Why not $teams["game"]["color"][] = $player?

In my BedWars Plugin, I simply use the color of the nametag.

You can make npcs or colored clay in the inventory

Create a fake chest tile when they hurt the villager.

You cant really create a fake tile. you need a chest (for example) being bound to this. I know how to spawn inventories.
I also mentioned this.

No bad idea.