I was absolutely amazed at how different (in personality) each of my chickens were. Even as chicks. But now that they are adults, it's even more noticable. I love 'em.
For the OP (original poster), the scariest time - in worrying about mortality - is in the first few days. I ALWAYS buy the chicks in the feed store bins which look like they are the oldest. The feed store gets its deliveries from the hatcheries on Thursdays, and I go in on Saturdays, looking for those that were delivered the previous week and didn't get sold then. If they've survived a week at the feed store, they're most likely going to continue to survive.
Of course, if there's a breed which sells out fast, and there aren't any "leftovers" from the prior week, then I have to buy chicks under a week old. (Say, hatched on Tuesday, arrived at the feed store on Thursday, I see 'em on Saturday.)
I usually just buy one of any breed, and pick up at least two breeds (can't go home with just ONE chick!) but if I can't find any I don't already have - in addition to the one I want - then I will buy two. That's how I came home with two Welsummers, and later, two Sebrights. Oh, and in between the Welsummers and Sebrights, there were those two bantam cochins.
Addicted? No, no way. I can stop any time I want to. When will I want to? I dunno. Sometime soon, I guess. Or not.