I must admit, this episode is kinda lame. I'm sorry but the whole probe thing was kind of stupid.

but one is inclined to ask...is that a drakh probe? it sure looks like it. makes me wonder what the shadows would think about one of their races undermining their plan for the survival of the fittest.

I lied the other plot... about the laison officer and G'kar

I thik the whole feel of the A plot was something more suited to Star Trek.
The subplot with Na'Far was good though. And it was good to see the return of that other Narn that Sheridan saved.

I wondered why they didn't ask the more advanced races for the answers to the probe's questions.

It is an interesting thought that the probe is Drakh in origin. I do think there is an explanation for why the Drakh would send it. They weren't trying to decide anything about whether to contact humans or not. The probe was simply there to take out the station, and the questions might be a red herring, or an effort to determine how advanced humans are before the Shadows try to help nature along. Why not blow up the station directly? The Shadows tried that before, and failed. It's possible that they want to make sure the Shadows' attempt, whose defeat is shown in War Without End, won't take place.