Soldier is fighting against an alien dog. In german, a dog.owner says 'Aus' if he wants the dog to stop whatever. what do you say to stop a dog from whatever? Other interesting dog commands?
We just say "stop" or "no", usually the latter. Some more commands would be: "wait" "stay" "heel" "sit" "[lay] down" "play dead" and depending on your release command "ok" or "release" or just about any other word.

Well, sometimes people make a mistake, or really screw something up, and they say "shoot". Hehe, I just look at them and say "bang".

Soldier is fighting against something that looks a bit like a spider. If somebody hates spiders and sees a spider (or smashes a spider) what would he say?
Depends on how much he hates spiders. I'd say something like: "Just what we needed, more spiders." or "Ick, spiders."