For the target, I'm unsure how thick a piece of styrofome should be, but I would recommend going to Wal Mart and picking up a styrofome target for $15. There are dots on each side of this target, so you can get alot of usage out of this target. When a side starts to get shotup, just flip it over and shot the sides instead of the front/back. When the sides get shotup, flip it around and shoot the top/bottom.

As far as the brisket shot, I pass on them. I'm sure there's some guys that swear by that shot and have had lots of success with it, but I'll pass on it far a broadside or quartering shot everytime. I've seen deer shot in the brisket with a 50 caliber muzzleloader, have a lung taken out and massive blood loss, go over 800 yards before expiring. Mind you, that was with a muzzleloader.