1) Yes, it did. Very much so and more mixed by the end. I don't really feel like going into was Prozac was like but, it was horrible!!!! I'd wake up after a few hours sleep and laugh and cry or just sit up, saying I was crazy and ...whatever.
2) Not that I know of? There is such a thing as mania induced by antidepressants that isn't bipolar disorder. Seems like an awful way to diagnosis. Mine was based on symptoms that happen when I'm not on any meds. Psychiatrist made a point to ask if this was when not on meds many times explaining how Prozac and Zoloft (I tried that one too), basically any antidepressant, can induce mania in people who don't have bipolar.
3) A mood stabilizer helping doesn't diagnose anything. Even lithium is used to treat unipolar depression sometimes. Yes, try. That's how psychiatry works. Try and see if it helps.
4) No personality change, bipolar isn't who I am. Mood stabilizer makes my mood swings a lot less extreme but, I definitely don't have a flat affect. Im just calmer, like waves rather than tsumani.

Sleep help? Eh-ish and depends on if you're on something more sedating too...racing thoughts yes.