Just a note for getting the Can't Touch This trophy. Instead of risking being surrounded by zombies, I found an easier way to get this trophy. I ran into an area in Moresby where there were a lot of zombs and I ran straight to an ambulance or a delivery truck shaped like an ambulance. If you jump up on the windshield part of the vehicle, they can't hit you (unless they are carrying a weapon) but you can still hit them. Just rinse and repeat until you have killed 15 in a row.
Note: You can use this method to get the 10 heads are better than one trophy too