to be clear, I am to use the genitive plural form whenever the noun is being quantified, independent of the context of the sentence. Right? Thanks.
Not quite. The case rules for nouns that follow numbers are a bit complex, you can find an exhaustive explanation under the tips and notes of the "Time and Numbers" skill. To sum it up, it's nominative singular after один, genitive singular after два, три and четыре, and genitive plural after anything else.