Momma will probably watch out for them where your other chickens are concerned but I would definitely watch them yourself too! I know a lot of people set up a space inside their existing coop or run that the littles can run in and get away from the Bigs if they need to.
Oh my crying out loud!! That second picture is stinking adorable!! Sex wise, too early to tell. Are they only using Momma for heat or are you using a heat lamp. If Momma is still caring for them I would give them so time outside with her. (I live in Washington too, Whatcom County so I know...