Concerning Istaris

[lathspell]

But what about Saruman? He wasn't killed, or was he? I don't suppose that a common man (Grima the Wormtongue) with a common knife could finally kill a Maia. Well, Gandalf had overpowered him and had cast him from the Order and from the Council, but by doing so had he deprived Saruman of all his powers? Anyway, where could he or his corrupted spirit go?

Saruman wasn't killed, but 'made bodyless'. An Istari cannot be killed for he can't die. I think that Saruman had the destiny as Sauron: to become a spirit which can never take shape again.
Yes, when Gandalf cast Saruman from the Order, he broke his staff and with that he deprived Saruman of all his powers except one: his voice. And that's how Saruman could still daunt the hobbits of the Shire, for they believed his words: him being a mighty wizard and all.

Orome (either Alatar and Pallando or only Alatar) and? Mandos & Nienna (Pallando?).

Later Tolkien writes that he thinks that Oromë sent both the Blue Istari for Oromë was the Vala with the greater knowledge of distant realms in the South and East.

Well, now the thing for what I came in here... a new question. It is said in UT that Gandalf wasn't planning to go with the Istari, but that Manwë and Varda asked him to go. In the end it was only Gandalf who fulfilled his quest (and maybe Radagast, but that is something I do not know. He was sent by Yavanna but with what purpose is unknown to me so I don't know if he failed). So, let's say that Gandalf was the only one... was this foresight of Manwë and Yavanna? They asked him to go and he is the only one to fulfill the quest. It's rather strange to me. So, is this coincidence or foresight?

greetings,
lathspell