mountains

Im a bit of a mountain buff and i was just wondering if tolkien ever specified how high the mountains really were, like whether some of the misty mountains could be compared to a mountain like Everest and so on. I think the mountains in the undying lands are the tallest but im not sure how each...

East of the Iron Hills are the Mountains of th east and the sea of Helcar but after the war of wrath were they separated from Middle Earth?

What about the Stone Giants!!! Well, are they real or not? Bilbo talks at length about some stone giants throwing rocks at each other and catching them, high up in the misty mountains during a thunderstorm. Even Thorin comments that they can't stick around with the giants there, and...