No, actually. It comes from the Latin "datum" and in Latin the singular "-um" becomes "-a" in the plural. So datum-->data. In your computer, the data refer to the billions of bits/bytes of information stored, etc., so it's TECHNICALLY a plural. HOWEVER, I would agree with you that "is" SHOULD indeed be accepted, because in common usage I pretty much only ever hear it used as a singular (although technically that's an incorrect usage). It's similar to how "panini" in English is actually a plural (panino-->panini) but people call it a singular. I would say you should report that, because even though it's not prescriptively correct, because "data" as a singular is so common in descriptive use/understanding, it should be counted (if it wasn't already)
Technically you are right, but in everyday day spoken English, you'll get funny looks by treating the word data as a plural countable noun, and not an uncountable noun.
I think it's because nothing except the adjective is preceding the noun, therefore it must take strong inflection.
Strong inflection is used: -When no article is used (<-- as is the case now) -When a quantity is indicated by: etwas (some; somewhat), mehr (more) wenig- (few), viel- (much; many), mehrer- (several; many), einig- (some) a number (greater than one, i.e. with no endings) non inflectable phrases: ein paar (a couple; a few), ein bisschen (a bit; a little bit)