It depends on a variety of factors. If he is molting excessively, it might be fleas, mites, or a variety of other parasites. The claws do that naturally with aging. If you are very worried, consult a vet.
because the bark of a tree could damage the cat's claws and the cat could get hurt badly.
A fungal infection could cause those symptoms.
a lobster can crack a shell with its claw and the claws help the lobster protect its self from predators
when they are shedding which is called molting it makes their new skin very soft and they could get hurt easily
A yellowish, discolored throat with red spots and a cough could be a sign of an allergy, upper respiratory infection, bruising, cancer or any other number of ailments. If symptoms persist or worsen, it would be best to get checked over by your doctor.
Common causes could be a power surge or overheating.
You could just take them to a vet
Yes, I would say porcupines have claws you just do not see them because of their sharp beck you could say.
No. it could easily be stepped on or thrown off the tree. it is the safest stage of its life though.
it could be afraid or it could be climbing up something or down something
You can't. It would be awesome if you could, but you can't.
They could hurt a human with it's sharp claws.