Yeah, you should be able to. I guess they are trying to emphasize that nouns before the olla verb deserve the word "the" before it, in stead of the "a" or "an". But you are right, it is not necessary to put it before both. It should be an alternative. Did you report it? Usually they pick up stuff via reports.
Yes, agreed- I gave it some thought and if we're using "where's" I'd drop the second "the" for sure, unless I was going for some emphasis on the dressing as a distinct focal point (e.g. "here's the salad and THE dressing!" but even that is really odd and not quite right.)
While I don't think "where are the salad and the dressing" is totally incorrect, it's definitely not something I'd say as a native speaker as it sounds awkward. I'd say "where's the salad and the dressing", mostly because they're a set that goes together (same with salt and pepper, I'd ask "where's" although "where are the salt and pepper" would work fine.) Now if we had an extensive list of items (oranges, peppers, lemons, and lettuce) I would probably bust out "where are" because they're not a set and there are a lot of them. However, I think there's a difference between saying "where's" as shorthand and "where is", if someone says "where is the salad and dressing" it's more awkward than the shorthand of "where's the salad and dressing". Having two "the"s would be similarly awkward, too, unless I was (for some reason) trying to add emphasis by adding in the second "the". In my experience anyways.
Same! There seems to be an obsession with translating to a clunky grammatical version English rather than the English that would actually be used. In my opinion translating to a normal version of English rather than the demanded grammatically formally correct shows a better understanding of the sentence and should be a correct translation option.