I don't know if this still works, but if you use ragnarok right at the end of a level, just before you get day end message, it counts as using it without having to fight them.
Mrboobaloo, look at the box in the lower left corner (your cannon info). There arrows on each side of the box pointing at which direction you will shoot.
99 Bullets - You need a chainsaw and whichever gun you want the ammo. Use the chainsaw, hold the mouse, and try to switch guns. the Chainsaws ammo will change to the ammo of your other gun. once it hits 0, it will reload to 99. stoop shooting and the ammo will return to the chainsaws current ammo. Switch guns, and your weapon will now have 99 bullets in it.
blockade the widow by using the hammer and nails on the barricade below the window (you can get mroe nails in the basement even with the zombie down there)
Also, you can stun using the second from bottom BMagic.
I like the random Gurren Lagann references (Pierce the Heavens & Fight the Powah, if you didn't know)
 "Tag Attack"){kind=icon}
 "Choose Your Weapon 3"){kind=icon}
 "Elona Shooter"){kind=icon}
 "I Can Hold My Breath Forever"){kind=icon}
 "Cursed Winds"){kind=icon}
 "Valthirian Arc"){kind=icon}
 "The Last Stand"){kind=icon}
 "Spikes Tend to Kill You"){kind=icon}
 "You are a..."){kind=icon}
 "Post it Draw it"){kind=icon}
 "I Remain"){kind=icon}
 "Alice is Dead - Ep 2"){kind=icon}
 "Epic Battle Fantasy 2"){kind=icon}
 "Storm the House 3"){kind=icon}
 "Elements"){kind=icon}
 "CycloManiacs"){kind=icon}
 "Medical School"){kind=icon}