Let's say the terms were limited to a small circle like you suggest. How is it that his college roommate that wasn't part of this circle knows the alleged meanings, yet no one outside the group in HS knew the meanings? IMO, that argument doesn't hold water.
As for the large segment of the U.S., they were never going to be happy with the choice because Trump. As for celebrating, I think many of those speaking out are doing so in direct response to the very public (and oft times unruly)demonstrations held by those opposed to Kavanaugh. If Kavanaugh had not been confirmed, do you doubt they would have loudly and publicly celebrated?
As for the last, I agree both parties keep moving further to the extreme, but there will always be those in the middle, and it's the middle that ultimately decides, IMO. When the left pulls such an obvious political stunt as they did with holding that accusation for weeks, they do not help themselves. When protesters line up to harass and bully the opposition, they do not help themselves. I think many of us in the middle expect a code of conduct that the left continually throws out the window. And yes, sometimes the right throws it out the window as well, but, IMO, it's far more common on the left.