Its not the red, its the KIND of red that says "boy". The red in the males, generally on the shoulders, will be deep almost mahogany red and shiny. Not necessarily like a mature rooster shiny, but it just has that look. The "red" in females will generally be more tan or caramel color, and more matte looking. I would however, probably guess boy on the first two. "Finch" definitely looks like a pullet, and I would tend toward pullets on the last two as well.The two barred ones not SFH. Blue in a juvenile doesn't necessarily mean girl either. Young roos can be VERY blue, but usually turn mostly red at maturity. Don't put your trust in others guesses though. It difficult sometimes. Just observe until you see pointed ,shiny, saddle feathers coming in. Then you KNOW its a roo. With experience you'll learn to recognize that "look", until then make your guesses and observe. You'll begin to notice subtle changes that will help you in future gender IDs. Good luck!