Is it possible to change health and ammo?

Er... isn't this the wrong category to post that in? Also to answer your question, yes.

You can Mooti.
For health:
Everything you need to mess with is in Base.rte\Actors. Coalition are the green solider guys. Brains are obviously the brains. Robots are robots. Etc.
Open the folder up for the actor you wanna modify and you should see an .ini (ie: Solider.ini in Coalition) and hit Ctrl-F if you're in Notepad. Type in "Health" and hit find next and you should see Health = Something. Change something to whatever you want it to be.
For ammo:
Hit up: Base.rte\Devices and do what is listed above, except replace "Health" with "RoundCount"

Hope that helps!

and Perpetual:
If you know how to something, elaborate. This forum is for helping people, not just telling them something is possible.

Lol, you've got to be kidding me.
That variable
'Health = 100'
may just do it.
Oh deary me...
lock this before someone decides he's a moron and flames his head off.