I don't think it'd be much of a spoiler to let you know Vir will be back. IIRC Stephen Furst had some other regular gig at the time so couldn't appear in as many episodes, so his character was "put on a bus."
Franklin's outburst was exceptional since, while yes, he was under extraordinary pressure, he's also a trained surgeon. Much like pilots, people in that profession aren't normally prone to being easily rattled, *especially* not in high stress situations. So it was indeed the stims and the exhaustion that pushed him over the edge.
What I liked about how the Narn rep was portrayed, is that he wasn't just some two faced snake out to protect himself by collaborating with the Centauri. He genuinely thought that what he was doing was for the benefit of his people (at least in the short term) and he was clearly having to swallow his pride just being in the same room as Londo.
I liked Garibaldi's response to Delenn over the whole eye for an eye thing.
Garibaldi: I'm an eye for an eye and tooth for a tooth kind of guy.
Delenn: So, you want everyone to be eyeless and toothless?
Garibaldi: Not everyone, only the bad guys.
Its probably the best response to the anti-eye for an eye argument that I've heard.
Really? I rather thought Delenn's expression at that said very loudly "and I suppose you get to point out who the bad guys are?"
She was just too polite to say it.