Looks like Morden helped Mollari in order to set up a war between the Centauri and Narn. After all, Mollari told his government that he himself would take care of Quadrant 37. So once G'Kar finds out, that should make a conflict inevitable.

Some more difficult things to guess at: what's up with Kosh, Delenn, the Minbari prophecy, Morden, the seer's vision of Babylon 5 blowing up, and The One.

Maybe Morden is working with the resistance forces on Earth; after all, they're always wanting to incite conflict between the aliens. There's something peculiar about the way Morden asked each of the ambassadors "what do you want" in Signs and Portents. It seemed as if he was probing around to see which of the races were most likely to be at each other's throats. From the responses, it was obviously the Narn and the Centauri. How Morden is in touch with so powerful friends, I don't know.
Kosh is obviously powerful. He seems to know a lot about what's going on: with Delenn, and with Morden (he tells Morden to leave and "they are not for you" in Signs and Portents). I don't have any idea what's under the encounter suit, or why it's damaged during that same episode, since he wasn't doing anything except talking to Morden.
I think Delenn and the Minbari prophecy is the most interesting so far. I guess the prophecy has to do with humans and Minbari working together. Delenn went into the cocoon in order to change into something more human. Again, don't know why she needs to do that. But The One appears to be Sinclair (aged), and the woman off screen should be Delenn. I'll make a wild guess to say that The One is the last surviving human in the universe, and the woman off-screen is also the last surviving Minbari in the universe. (but I can't imagine a TV show with just one human; that's hard to pull off). When we saw them they were travelling backwards in time to avert a major war. Maybe that's why The One looks like an aged Sinclair- he was from the future. There's also a possibility that the Minbari and the Humans are actually related, and evolved differently. And the Minbari obviously did something to Sinclair while he was captured- that's why he had to have part of his memory wiped/blocked. I think they took a blood sample because they wanted his genes. Ever since, they've been breeding some Minbari-Human clone, which resulted in that hairy-looking alien in Babylon squared (found on Babylon 4). That's why the scientists there couldn't figure out what race the guy was from, but he was obviously working with The One (Sinclair), and the woman.
As for the seer's vision- she said it may or may not be the future. If it is, it could be just a consequence of the war that's coming.

I thought the most logical reason for the Minbari to surrender to Earth was because they were somehow related. Makes sense, doesn't it? I didn't guess it was something to do with the souls, but I was on the right track, or thereabouts.