While you've already received a flood of invaluable advice, here's my take

:
1) Why do I have to separate the cockerel at this time from the pullets if chickens are supposed to be flock animals?
There's no rule stating cockerels must be separated from the flock. I rarely do, unless it's necessary to keep the peace until culling time. Provided he's well-behaved, allowing him to socialize is best.
2) I am kind of hoping I do get a cockerel because we have ~2 acres, with NO trees for protection, and have hawks, hawks, and hawks. I would like that "Alarm" system in place to protect the flock. But, is it naive of me to keep the cockerel when there is a possible chance he could create total mayhem to me and the flock?
No worries, it's not naive.

The fact you're so cautious proves otherwise. While he
could theoretically cause distress to all involved, there aren't any guarantees. You don't know until you try! What if a perfect, model roo is the end result?
3) I have done only research on hens and have no clue about roosters. If I do end up with a cockerel or two, should I just cull it (them) since this is my first rodeo?
It's entirely up to you. However, the first cockerel would serve as a wonderful learning experience, if nothing else. We gain deeper understanding from our mistakes (not implying you will make any....but I certainly did initially!

) and successes.
4) Because I selected docile breeds (except for maybe the Wyandotte), does that docile nature known for the pullets/hens apply to the cockerels/roosters as well?
Not necessarily. Most I know claim Silkies, Brahmas, and Cochins are among the most docile. My experiences with them were, for the most part, awful. (though it's entirely possible they were mere victims of my past, errant method of raising cockerels, which turned out nothing but human aggressive jerks

)
Most of all, have fun along the way.
~Alex