Yes, there's no Alt-Bell that we've seen either yet, but Bell himself is such an enigma, it wouldn't surprise me if that revelation was more along the lines of how the other Bell died or something? (Though again I'm speculating and you make a very good point - perhaps Alternina is off with Alterbell). But Nina's absence seems conspicuous to me, although like you I did not notice it right away.

I did forget about the light switching off! But I think I'd group that under "universal" powers since it seemed to be one of the first tests the ZFT had for future soldiers (by which I believe they meant Cortexikids *insert hazy memory here!*) So I don't know that that was specific to her either, or just a box wired up to respond to specific improved Cotexiphan perception or something?

As to the traveling from one universe to another, I thought that was because they had been using their powers the night before, especially Cancerman? It was a bit of a lame piece of technobabble from Walter but it seemed that Cancerman's extreme use of his powers kind of screwed the stability of the transfer and it was manifesting by everyone's powers either becoming uncontrollable or ceasing to work. But if Olivia is totally cut off from her power, like her memories of early childhood, then that would explain why she wasn't affected?

I hadn't thought of Alt-strid being a cyborg! That's pretty cool and would make a lot of sense given their technological advancement and use of cyborgs to travel to our world since they're hardier. Cyborgs are obviously Things They Have.