^Good Question(s).
I think free speech is surely needed. In the limit situation -- where you have a very "mature" society, with strong institutions, you can have 100% free speech, as you can trust garbage hate speech will end in the... garbage. I do understand that we are far from that situation, and sometimes it is in the interest of the many to control free speech (even if in 9 out of 10 times this power is not wisely used).
I do not think PC is needed, at all. That's my main point all along. I think that some goals of political correctness are always to be desired. I would love to see people respecting each other, taking care about how each group feels and etc, but I do not think this is something that should be enforced. Encouraged, maybe. Once you force people to be nice, being nice means nothing. You cannot enforce people to respect everything around them. Hell, there is a lot of things I don't respect, and I can guarantee nothing in the world would force me to.
Anyway your question was about extents. I guess that this is completely case specific.