My guess would be that the ball was a second and used just to give out with/for sigs. In other words, it wasn't "good enough" for league play but still tossed around just fine. :)
Baseball Stamps.
This is too vague a question to answer. The value will depend on if we are talking about old US postage stamps with a baseball theme, or a type of sticker stamp found in gum and/or...
The way to get autographed Baseballs is to either get there early and try to get near them before they get on the field, sit close to the dugout and ask them when they start, be freinds with someone...