For minimal damage but still good stopping power i would say either a 5 or 6 shot 12ga.
Although if your not going to eat the animal a 3 shot is the best
It may vary depending on the game, #6 for squirrels and quail and rabbit, 7 1/2 or 8s for doves.
It will depend on what you are hunting and which brand of shell your shotgun patterns best.
Extra full
A shotgun is the only legal firearm for duck hunting in the US.
Slugs! If its rifled it is a deer hunting barrel.
depends on the use. Hunting? paper or home protection? Federal Winchester or Remington make ammo for this. There are surplus ammo you can find at a lower price them commercial hunting or match ammo. Make sure the surplus ammo does not have corrosive primers.
The one that the man is carrying!
modified
Best would depend on intended use. Federal makes good 30-06 ammo. Soft point for hunting, FMJ for target use.
remington 870 12 gague
Well all the stores are closed because of the zombie apocalypse, and you need to conserve ammo! That is probably the most improtant part of Undead Nightmare! The only way you can get ammo is by killing Zombies who have ammo on them.
That will depend on the individual. Some will prefer a shotgun and others a rifle.