We know there's a Bridge Officer's Exam - we see Troi take it, infact. Odds are neither Paris not Torres ever did, making Kim (who has) the probable number 4 since he mans the 'night' shift.
It's inconsistent writing that it's not dealt with, but there are a number of explanations - most likely imo being that Seven (who is effectively in a paranoid psychosis) is essentially seeing what she expects to see. Even with apparently "clear cut" information such as static images, the human mind does a huge amount of interpretative work, leading to people having quite different perceptions of identical stimuli.
Locutus exist for a matter of days at most, Seven was a drone for several years. I've seen fairly convincing arguments before that the Borg are engaged in an iterative assimilation/adaptation processes, and that there's not a simple three step [base organism]>[borg zombie]>[borg drone] process. It's quite possible that Locutus had no cortical node, whatever that is, or that it was minor and not fully integrated into his important grey matter.
Neither. She's dead before Voyager returns to Earth. There's that little timeline blip where Admiral Janeway decides to throw every rule she's not broken out yet out the window, but the Temporal Integrity Commission would tie that up in fairly short order.
Less facetiously, if she did make it back, Starfleet and The Federation make a point of not behaving the way you describe. Half the point of the series (especially TNG) is that these future-Humans are better than us. We would no more give Data any rights as a sentient being ("lol, it's a machine - idiot") than the Federation would chuck Seven into space-Gitmo because she was brown and had a scary beard was an ex-borg. In most post-Voyager content, IIRC, she ends up heading a research group looking into anti-Borg solutions, then quits in a huff when Starfleet decides (again) that they've not shown up for a decade or two so they probable won't.