How do you get autographs from baseball players?

Our vacations are visiting ballparks during the summer. How do you get baseball players autographs? Before at batting practice or after games when they leave? Is that impolite to hang out after a game? My son (7) loves to get autographs and my husband and I are always arguing what to say or do at the moment. Any tips would be appreciated. Season’s coming soon!

What is the baseball players chewing on?

Almost all of the baseball players are spitting out seeds.
Is there a special food that they chew on?

Why do baseball players throw their equipment (bat, helmet) after they go down strike out. I see it in Major League Games all the time??

Why do they do it???