To reuse the insect analogy, there might not *be* only one single over-riding 'leader' of the Borg. The queen might just be the queen of one particular collective or another, while all the other 'collectives' of Borg might have other queens. Kind of like, Ants have no single leader, but one hive of Ants might have only one queen, while another hive has got a different queen ant. The ones on Voyager might reasonably be completely different Borg Queens (despite Alice Krige coming back to play the one in "Endgame"). This still doesn't preclude the possibility of all the individual Borg Queens sharing a single mind within themselves (and each other?).
It was established in the movie itself that a version of the Queen was already killed once during Best Of Both Worlds. That didn't kill the entire Collective either. So if you really asumed that the Borg were destroyed, you weren't paying attention.
The idea that the Borg were a collective was the only interesting thing about them. FC turned them into a "hive" -- b-movie crap.
Fighting against a faceless foe with no leader isn't very dramatically satisfying, though. You need to have an actor/actress that gets defeated. The TNG writers immediately realized that problem which is why they created Locutus for the second appearance of the Borg.
No, you don't. The fact that the studio believed that to be true is insulting to the intelligence off the viewer/movie-goer. It's the lack of a face and personality and their utter indifference which made the Borg more like an unstoppable force of nature than an Evil Villain[TM]. A "collective" is interesting; a "hive" has been done to death in a million crappy horror flicks.
I think Hollywood subscribes to the theory that "nobody ever went broke underestimating the intelligence of the American public."