you have to eat a chicken testicle
To get that farm banner on Zombie Farm, you've got to win an invasion and have some luck with the loot you get.
you get a zombutterfly
It will not become a "lifeless" zombie if harvested when you have no life available to give it.
I'd say the fems and mutated Minis
though nothing will happen :p
You have to invade I'm pretty sure it can be any invasion and if you get 3 you get the mausoleum key
Yes, you can get rusty fragments from successful invasions. The chance of getting one is random.
yes
Nothing
If you invade every time you can, your zombies are not hungry. Track their hunger on the zombie status screen. The more hungry they are, the less likely they are to get distracted. At starving, they never get distracted. After each invasion they are full.
It makes your crops worth double their money but I don't know what happens to fertilized zombies
You cant. Thats in Plants vs. zombies, not zombie farm.