Everything so far is going very well with the girls. I just helped my friend incubate so I have 5 little chicks currently in a home made brooder box. how do I tell if the chicks are hens or roosters? and at what age should I be able to introduce them to the other chickens especially considering its already getting pretty cold out, really chilly at night! will I need to move their heat lamp to the coop for a bit?