Homesteading newbie: ready to learn!

MY NAME IS GABRIELLA, in central FLORIDA. I've referred to BYC often while starting out on my road to all things chickens, but finally decided today I should introduced myself after getting an additional 7 chicks yesterday. I've built a coop! Woowhoo, thankful for the forums on here I was able to refer to. It's 4x4 standing on 18" legs and an attached nesting box (if anyone cares I'll post a pic ). We have had several chickens while living on this particular piece of land but unfortunately there is prey that has consistently plucked them off (pun intended ). Now I've built a proper coop, invested a little more in the security of my other animals (we also have a small herd of goats). Three weeks ago I bought 8 bantams, yesterday we brought home four road island reds and three of another breed that we unfortunately don't remember what were called . The road islands mixed right in with our bantams but it seemed like the bantams were picking on my other three, so I separated them. I'm learning about chickens and will be the first to say I don't know much about them or their behavior. I am willing to learn and Im dedicated to doing things right. My husband however is a big believer in letting nature handle all things animals- not me. My flock will be free roaming as some point, but when? do you think the coop will be big enough? How can I mix the rest of my birds? How long before I should start training them to live in their coop? I currently bring them inside every evening due to owls (etc.) that have made earlier chicks food because of the makeshift brooder we are using not being prey proof.
I'll be scanning the forums for additional informations and wisdom! Thanks for your time....