>Stainless steel is generally not magnetic and every magnet I've tried when making my dustcover sticks to it quit readily.
As someone has already noted, different grades of stainless are more or less magnetic. The grades used for firearms are as magnetic as any other steel. Generally, the grades used for things like stainless steel refrigerators and other appliances are not (one reason not to buy a stainless refrigerator, if you are the type who likes to post kids' pictures, appointment cards, grocery lists, etc., on the fridge!)
As for corrosion resistance -- I have a couple of non-stainless guns that have zero finish on them -- but also zero corrosion. Oil on them does much, much more for corrosion resistance than bluing (which actually has virtually zero corrosion resistance), and even stainless will rust unless protected, just not as quickly as unprotected standard steels. "Traditional" finishes like bluing or Parkerizing do little more than enhance appearance and, in the case of Parkerizing, provide a rougher surface that holds more oil.
