Claws? I assume you mean toenails? The nail just grows like any nail does. Most chickens that are out and about scratching in the dirt wear their toenails down naturally. Perhaps the birds that you bought did not have the opportunity. Although, all of mine are out and about scratching all day long and some still need their toenails clipped from time to time!
So, every now and then, while they are all perched and ready for bed, I make sure to take note of the toes sticking out from under feathers and give pedicures to any bird that needs it!
To trim the nails, you can use human nail clippers (the large kind for toenails) or buy a pair of dog toenail clippers (safer, I think, and that is what I use). Only clip off the very end of the nail; any farther up is the quick the vein that supplies blood to the nail (just like a cat or dog). Have some corn starch ready to stop any bleeding just in case. I always make sure to have it on hand, even though after all of these years I still havent cropped a toe nail close enough to cause bleeding. An ounce of prevention is worth a pound of cure.
Im not sure about the spurs telling the age of the bird. He could just have really long spurs. Although, I do have an 8 year old Phoenix rooster who has spurs that are so long they curl right back around and come within half an inch of his leg. I'm sure the sharp point would actually and eventually touch his leg, but I clip it back frequently just so it doesnt happen!
I hope that helps! Good luck.