As long as the bird is healthy, nothing will happen to the bird after several days. However, if the bird is sick, it could possible die after several days.
The bird's body digests it, and it serves to nourish the bird.
You need to go to Kakariko Village, once your there go to the statue of the bird, then play the flute. The statue bird will break and reveal a real bird inside it. Which will carry you to several places when you play the flute.
The noisy bird is a mockingbird (there are several species).
Nothing, as a lot of men wear their underwear more than several weeks (I mean days!).
He crashes
5 days old
It will eventually be ground down into a round rock, then gravel, and finally sand.
during an upstroke wings of the bird move upwards.
it dies
it is digested
nothing
It will get its' fill of blood, and grow larger. Once it's had enough blood it will detach.