The premise of the movie (spoilers here) was that the corporation that ran the mining operation knew, at the very least, that there was alien tech down there and wanted it for military use (those evil corporations!) The android was secretly in on this plan, which is why he overrode the crew when they tried reasonable quarantine measures, or wanted to attack the small alien.

Yes, I agree the acid was "magic," but it served the plot's function of preventing the crew from using any method of destroying the alien that might endanger the function of the ship.

Another irritating cliche--is it really useful during an emergency to fill the halls with steam and start firing strobe lights everywhere?

But then I was at the New York airport during the great blackout of 2003, and damned if they didn't start firing strobe lights for emergency lighting! At least there was no steam, but when I was in the john going to the bathroom under a flashing strobe, I did get some "Alien" flashbacks. I knew that if I was in a movie, something nasty would have come out of one of the stalls. Other than the smell, that is.