Cokin P Filter Holder - Two questions

1-Anyone know of a store in the south Florida Boca area where I can buy an 82mm adapter ring? A friend is generously loaning me his 16-35mm lens for an upcoming trip and it calls for 82mm. I know I can order it from the web, and I will if I have to, but it seems dumb to pay shipping for a $10 part.

2-I have two P holders, and I have this issue with both of them: When I have the circular polarizer and second filter in there, like a ND or a grad, I can move the second filter up and down easily, no problem. However, when I add a third filter, like another grad, it is extremely difficult to move the third filter up and down. The third filter is in the slot furthert away from the lens. Is this user error, or does this happen to you, too?

Thanks in advance, everyone.