I just purchased an 870 Express which is about 3 years old but still in the box. I bought it from a friend who won it at a raffle. It has a 21" barrel with special turkey choke. I plan to use it for sport shooting, home defense and maybe deer next year. Three questions. First, it has what seems to be a light coat of surface rust on the barrel. I'm sure it will clean up but looking for a suggestion on what product is best to use. Second, what do you think of a 21” barrel as an “all around-general purpose” barrel. And third, what choke would be good for the uses I have stated? BTW the safety is the old non-PC version. TIA for any replies. BigAl