I am newish to raising and hatching out chickens as well and I just had my number one lesson handed to me this weekend and this morning. Some, hopefully not many, of your precious fluffy sweet chicks will die. That is a part of life and nature. Do your best not to beat yourself up over it. Most situations are out of your control. Do what you need to do to grieve and then move on and tend to your chicks.
Second, like many many many pp have said, build your coop twice (at least) as big as you are thinking right now. Trust me, it will be worth it in the end by not having to "piece mill" your first coop to make it bigger and probably having it cost more to build.
Third, again like pp are saying, they are chicken, not anything else. Just a chicken. They do however have fantastic personalities and behaviors. Enjoy that and absorb it in. That's what it's all about, at least for me. When I'm having a crummy day, I walk out to my chicken coop and watch my chickens run and it cracks me up. The way their little legs go so fast and their necks sway back and forth....makes me feel a whole lot better.
Good luck to you in your chicken adventure!