Sulfites are very different from sulfates. Sulfate is necessary for life, but if it's attached to certain other chemicals it can be disastrous. Sulfites are SO3 2- and sulfate is SO4-.
Poor little Johnny,
Of him we'll hear no more,
For what he thought was H2O,
You can find dozens, if not hundreds, of lists of foods containing sulfites. Most of them are just copies of other lists.
As for how much sulfite is in a food, there is a good website that has how to calculate how much sulfite is in your food:www.learningtarget.com/nosulfites/index.htm