The Captivity of Maedhros

[AndMorgothCame.]

While a captive of Melkor off the peaks of Thangorodrim, Maedhros somehow lived for years hanging literally by his wrist, which was bound to the precipice by unbreakable metal. Later told, he was saved by his cousin Fingon, for which the latter grew renown. I remember reading it was around 24-32 years Maedhros was hung by his wrist. As well, Elves can go very long without food, if they even need to eat regularly at all? (I know they have no regular sleep patterns) Can you imagine such an excruciating pain? When I wake up with an arm or a leg still asleep, I can hardly stand it!
My main questions are: Exactly how long did Maedhros hang from the cliff face, and how did he survive without food and water? Or if he was fed, who did it? Morgoth knows no pity, but perhaps he kept him alive to keep the torture going.
Let me hear your theories/facts.