Two kinds of tin cloth- oiled and dry finish. The dry finish is no different than any other clothing, throw it in the washer when it needs it. Oiled finish is different. Wash it and the oil finish will go away but you can re apply it. Oil finish garments usually turn very dark over time with wear. Size is as marked, no different from any other clothing.
I have a bunch of tin cloth stuff both dry and oiled- double bibs, double pants, a few jackets etc some more than 10 years old. None show excessive wear except a bit of fraying arond the cuffs on the older ones. Oiled tin cloth is not something you want to wear in warm weather either. Imagine wearing clothing made from a lawn and leaf bag and you get the idea. Rain won't get through but you will sweat enough to make up for it. And when its really cold, oiled tin cloth is like waxed caedboard until it breaks in.