LadyLavinia said:
1. Why was it necessary for Angel to destroy the Circle of the Black Thorn at that moment? Did he ever consider that the Senior Partners would strike back with an apocalypse, in order to kill him?
I agree with AshSan and Jenny on this one. The apocalypse was already here in that demon influence was encouraging the dark side of man to destroy itself. Angel saw no way to completely stop this. It was built into the nature of demons and man. He could only slow it down, and send a message to the demon side of the equation, by destroying the SPs immediate power centre in this reality.
2. What exactly was the Bejoxa's Eye trying to tell Giles and Anya?
I agree with Karrin Murphy's answer.
3. Why was Angel so important to TPTB (in details), when Buffy, the other Slayers, Spike and Willow all proved to have bigger impacts upon the supernatural world?
I agree with Lady Lavina here in that there does seem to be a distinction between the PTB on Angel, and the influences that motivate Buffy.
Personally, I've always seen the PTB as kind of police men enforcing mystic law to stablize the balance between good and evil. In my opinion, I don't see how they come out strongly on one side of the equation or the other. Buffy and hers seem to dance to the music of a higher power.
I think whether or not you recognize the PTB as the highest power in either verse, or choose to see the presence of something larger is a matter of how you personally choose to enjoy the show.
4. How can vampires be soulless, when they have the ability to express emotions, like humans?
Again I think this matter of how you choose to view the show.
What works for me is I see human emotion as existing on 3 levels - instinctual, physical, and spiritual. A vampire can love on the first 2 levels, but is incapable of what I'll hypothesize as spiritual love.
5. Does having a demonic soul automaticallly mean a lack of conscience?
There's no such thing as a demonic soul in the Buffy/Angelverse that I know of. If demon characters such as Doyle or Lorne have souls there is never any suggestion that is different than any other kind of soul.
Vampires are different. They are a raw demon spirit shaped in a human form. I see them as something more like the demon energy that empowers the slayer. They don't have a conscience in the B/Averse. We know this because the writers constantly tell us this. In my opinion they lack anything like direction on a spiritual level of what good and evil is.
6. Why do so many people believed that Buffy had a "sacred duty", when the Slayer line had been created by ancient African shamans, and not TPTB?
Again I agree with Lady Lavina. This baffles me too.
The only sacred duty Buffy has is the one she chose for herself. The rest is the manipulation of people of questionable motives empowering her with special power from demon energy.
On the other hand I have this personal theory, she does have something larger watching over her. There's stuff like the snow in Amends, or the times in her battles with the Master, and the First, when she rose stronger than before, that seem to suggest this. I personally don't think that was the PTB.
7. Was Willow really the most powerful witch ever? Or was she simply the most powerful witch to ever live in Sunnydale?
As presented by the time of Chosen Willow was da bomb. No other witch presented thus far in B/A could touch her. Even Miss Harkness and the other powerful witches of the Coventry Coven were intimitated by her.
This doesn't mean Joss can't introduce a witch in the future capable of handing Willow her mystic butt.
8. Did Wes and Fred forget about their conversation about Lilah, Cordelia, and Connor in "Players", when their memories of Connor had been taken away?
Not exactly, or necessarily. Wes refers to the Cyvus Vance spell as a "reality shift", meaning some of what happened in the old time line is available to their memory. Some is not. What is or is not, only Joss and Cyvus Vance know for sure.
9. Why didn't Angel or Wes bother to ask Spike about how he had acquired his soul?
Often of what happens in B/A appears to happen off screen. A few examples would be how Willow and Buffy know what the scythe is capable of, how Buffy, the Scoobs and the First know Buffy has been re-introduced into the Slayer line, or how Lorne knows what Angel requires of him in Not Fade Away.