Well, I still gave my thoughts about the holo tech.
As for the unkown character, if I remember correctly, I think he's human. His hair, body features (that could be deserned), and clothing, lead to either human, or one of the species that have the basic siiloete of a human (Bajorians are one).
Romulans and Vulcans could be ruled out, their hairstyle's different from the badguy's (again, if I remember correctly, and their hairstyles are pretty consistent from character to character); Klingon's ridges and body shape would be easily detectable; Carasians, Kazon, and other 'headgear' (the actors have to wear big ruber masks and body apperance mods) just didn't match the siloelete.
To talk about your thoughts alittle (not insulting, just observeing and thinking):
1. He's from a alt universe, so time travel to our universe's past may be a little difficult, even for Treknobable. But that would be an interesting plot twist.
2. Naw. It's Kirk, I mean, why would HE come back to screw the Federation?
3. Sela (sp), was her name, but the badguys (again, if I remember correctly) had the profile of a man, and not one of a Romulan female.
4. Lor? Thought he was blown up or dismattled? Have to watch the TNG episodes that he was in. But that would be an interesting plot twist also. Do like in First Contact, go to the past, contact the Borg, or something like that. But I really don't know why he'd go back to screw the Fed.
Ah, well, trying to figure out who or what Trek badies are is really confuseing, and it's usually better to just let the writers explain it.
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This is it. That moment they told us about in high school, where one day, algebra would save our lives.
'Evacuate? In our moment of triumph?'
Grand Moff Tarkin, just before the Death Star blew.
We are Dyslexia of Borg, futility is resistant, your *** will be laminated.