A few questions
 

I've a few questions on the creatures of Middle Earth, so please help me!

Where in the Misty Mountains do the Eagles (giant ones) live?

Where did the winged beasts of the Nazguls come from? Where in Mordor do they live, and are there more than nine of them?

Where do the orcs come from? (the movie said that they were once elves, but multilated to become orcs!!)

From the Hobbit we learn that at least some of the eagles lived in th enorth of the misty mountians. The Lord of Eagles that rescued the Gandalf, the Dwarves and Bilbo could sens from his outlock-post the "uproar" of the wolfcircle burned by Gandalf. When we suppose that he was then not far from home, as he could summone many of his folk, his eyeries have to be in the north of the misty mountains, not far from the high pass from Rivendell to the old ford.

The winged staeds of the Nazgûl are in the Lord of Ring discriped as a reminder of an older time. And as Tolkien stated in one of his Letters that fits very well their Petraodactylus like discription.
Were they lived we do not know, but since it is told that Sauron feeded them to become greater and usefull for the Nazgûl to ride on, we can argue that at least the gigant once lived at or near to Barad-dûr.
Legolas did shot one of the steads during the journey down Anduin and Éowyn killed one during the Battle of the Pelenor-fields. But still we see eight Nazgûl on winged steads at the Battle before the Morannon. That makes at least ten not nine and I think Sauron had more than ten of the beasts at hand.

That the Orcs were twisted Elves is one of the many theories that Tolkien himself ponder for a long time. Since it is given in The Silmarillion (which is regarded as the ultimate source at these board) to the loremasters of the elves, it has some authority. But Tolkien late in his life consider many alternativ sources for the Orcs ranging from Maiar of less power ofer Elves, Men and monkey like beasts to puppets preforming the will of the dark lord without independent live. So I give no clear answer to that question and can only wake interest in study of the sources to get an oferview about tolkien idea (it is worth the hard work it bears).

Respectfully
Findegil

Thanks for your help, Findegil! Your answers are informative and helpful.

Regards,
Bill

Well, I agree with what Findegil said about the Eagles and Nazgûl, but I have something to add about the orcs. When Christopher Tolkien published The Silmarillion, he published what he believed was JRRT's most recent work. That being said, when Elves first came to Arda (the world) Melkor (the first dark lord) captured them and I would recommend the Sil to you. It is a great book filled with information that should answer some of your questions.

About the origin of Orcs I recommend you read this article written by HerenIstarion, in may opinion it gives the best answer to this question ;)

All about Orcs