Taming Chicks To be Handled as Adults?

I started with 5 Easter Egger (Ameraucana) chicks in my flock and have had them ever since they first arrived at the store. I recently expanded my flock to a Black Australorp and a Barred Rock. The Easter Eggers don't mind being handled, with exception of one, whom I cannot seem to get to like me or anyone else, but I found that I am having trouble getting the Barred Rock and Black Australorp tamed. (I got the Easter Eggers when they were about two days old, and The Barred Rock and Black Australorp when they were around a week and a half.) Having tamed hens will make the many years to come easier for me and my family, so how can I get them used to being pet, held and comfortable with/around people?

Side Note: Do I have to start training them now to return to the coop after letting them out? They are living in a brooder now, but I plan on letting them have free range of my yard when they are older (while I'm outside watching them), and I want to make sure I will be able to get them back in the coop when their hens, without a struggle. When, and how should I go about training them to do so?
(They are all around a week and a half/two weeks old.)

Thank you!

Take the chicks and bring 2 or 3 of them in the house with you for short times - when you are sitting and reading, or watching TV. They will learn that you are not dangerous. When they are older and can start eating things other than chick feed, more like 5 or 6 weeks, take a little container and put some scratch or oatmeal in it. Shake the can before feeding them, so they learn to associate the sound with treats. My birds only get treat in their run or coop, not out in the yard, so when they hear "Chick-chick-chick" and the can shaking, they run for the run door.

Right on! Food is the way to train your chicks!

While they're in the brooder, use the same container and the same key word(s) every time you offer treats. They key into those cues very fast.

If you have a top access brooder, it's more difficult to interact with them so they aren't afraid. If you keep approaching them from above, simulating a predator attack, it's going to be very hard to get them to trust you.

You need to bring your hand in from the side, very hard unless the brooder has a side access, and come at them on their level.

If they are old enough to take outside, two or three weeks old with temps in the 70s, the taming process will begin to get easier. Get down on their level, approach slowly from the side, and begin teaching them to come to you using treats.

I find it useful to place a treat in a cupped hand, and with the other hand, peck at the treat with my finger. This simulates a mama hen calling a chick's attention to something good to eat, and the chicks will run to you every time. This holds over to adulthood, and I often don't even need a container of goodies to get my chickens to come to me. This hand signal is enough.