The magsafe adapter is covered by warranty and extended warranty.
Yes, normal wear and tear. Should not fail just because you are using it, like it is meant to be used.
If it is not working it is not working.
check warranty https://selfsolve.apple.com/agreementWarrantyDynamic.do
If you are not near a store, they will ship you a new one, with prepaid postage to ship the defective one back.
I got one 22 hours later and still had 2 hours left on my battery. Yeh apple.
One lesson can be learned here- do not wrap the cord like that, too much stress. You might be out of warranty next time.