In a battle, I noticed that everyone has a yellow diamond with a number in it, both my party members and the monsters we are fighting. What do those mean?
This yellow diamonds represents the player/monster's turn order. You may test that. Create a combat and check the numbers: the (1) goes for the first one to attack and then goes.
I've been lurking on the internet looking for Knights of Pen and Paper threads/posts/etc and I found your thread. I'm one of Behold Studio devs. You may contact us at firstname.lastname@example.org if you'd like.