Your respiratory system isn't the only that can be harmed from exposure to nuclear radiation, let alone any form of radiation (if i'm not wrong)
Most types, i believe so. but they can enter through your pores, or basically on your skin, and alter your skin cell division, hence skin cancer
Radiation like that can cause massive accounts of cancer on an international level since USA won't be the only people affected other than Japan of course. Trades across the sea, any resources (be it foods, plants etc; ) in the Pacific Ocean, birds passing through the area for migration or whatever they're doing, sailors, the list is endless