It seems like you are missing a "}" somewhere. try matching all the open and closing ones together and see if all the opening ones have a closing one!!

Yes, you can create a mod with the mod tools, and when you get in the game run the mod. Then you can load up the map and whatever you made in the mod will work on any map

is there a way to get an airstrike or something in my map that kills zombies? if so, can anyone help me with that?

How did you made it?

There is an option in APE that you can select and it will make it revive the player

Maybe try my way? the function it comes from does all the calculations so it might increase the health per round. Also, taking it out of the while loop might make it work if it doesn't work with the loop

Yea, I was afraid that the zombies might have a fixed health this way. Hopefully the riser thing works