Zombie Genocide Achievement Question.
1: If you get this achievement and get the ending where you leave in the copter with the survivors, will you get to use the Real Mega Buster in the other modes?
Yes.
Back to Topic Question. 3 Questions.
1: Do the weapons respawn?
2: Do you have to kill the Vietnam Vet to get the Survival Book?
3: If used with all of the health books together, how many days worth of food will you have?
1. Yes. Weapons respawn in all modes.
2. Not in infinity mode. The book will be on the ground behind the gated area. Just open the gate and grab it.
3. Not sure on that. Be sure to defeat as many bosses and survivors as you can so you can get their food items. Food items will not respawn in infinity mode. As long as you do not move a food item from its normal placement it will be there when you return. For boss food items, you must grab them while you remain in that current area. If you leave that area, the boss' items will dissappear - that is why I recommend that you plan to stay in Leisure Park for a while once you defeat the psychopaths there, since they each drop 3 food items.
Oh, and a little note about the unlockables - if you beat 72 Hour Mode and unlock the Real Mega Buster, and continue into Overtime Mode directly after that (aka. you met the requirements for ending A), the item will NOT be unlocked until you start a new game in any of the modes. In other words, it will not be available in that Overtime Mode continued from 72 Hour Mode, but it will be available when you start any mode from the title screen.