All right, look. You're 14, you obviously haven't completed basic high school biology or chemistry, and you definitely don't have any engineering background.
How about
learning these things before using them in your theories?
Acids of any kind are not an energy source. They don't give off energy, they don't make energy, and they don't absorb energy.
Acids are simply substances with a low pH. They break down other substances into simpler forms.
There is no way that acid can power any creature.
The second jaw from the original Alien doesn't have a hole, but you never see the back of the xenomorphs's normal mouth.
The xenomorph from Alien 3 was putting that meat somewhere, and I highly doubt that it was storing it in its non-existant cheeks for winter.
A "voice box" (they're called vocal chords) does not make the sound we hear of something breathing.
The sound of breathing comes from air rushing into lungs or some other body cavity, and is audible from the friction generated as it passes through a body.
Vocal chords only make nose if air can pass over them. If xenomorphs don't have a hole for air to move through, as you claim, then you couldn't hear the "voice box," now could you?
Oh, and if you want to go from your "robot" theory, then consider this: sound waves only travel where there is air.