2) During her travel to find Yennefer and Geralt, Ciri travels trough different times and worlds. Some seem to be european countries at different times (and historic events?). Is there any analysis of her different travel stations?
Well, it is known that Sapkowski is a big fan of the Arthurian legend.
You can see many parallels to it in the Witcher (isle of Avalon - isle of Avallach, Sir Galahad.. etc).
Basically the book hints at Ciri being in the Arthurian version of England.
And she also visits a Mediterranean port (could be Genoa) where she brings the Catriona plague
into the world of the Witcher, which is in essence the bubonic plague.
3)What was the exact purpose of the elves from the other world. I thought, they wanted Ciri to open the gate which allows to travel larger groups easily between different world. But why does Avallach and the King want her child and not just use her for this? If I understand it right, the King of the Raiders doesn't think they need their child. He thinks she is able to open the gate, so he is hunting her.
Ithlinne's prophecy says that her grandchild will rule the world.
But even if you don't believe in it, it's more than logical: to keep the bloodline of Lara Dorren alive.
Should Ciri die, there is no one left to use these powers. And why miss out on them ?
The Aen Elle could want to expand much further than just two worlds...
5) Where does Witchers came from? I though they are common humans, which undergo the mutation? But if I remember correctly someone in the books said, they came during the the conjunction of the spheres to the world. So which one is true?
Nah, you misread this.
It's monsters who came to the world during the conjunction of the spheres.
