Same as where you are: 1 pound = 0.45359237 kilograms Same all over the world: 1 pound = 0.45359237 kilograms
That depends on the size, shape and weight of the item, ask in your local post office.
500 first class stamps would cost: Well it depends where you get them from!!! :)
US Posrage - First Class - 44 cents as of 10-29-11
41 pence