Wow, another tall order. Okay...
First, some general blathering. The expo was absolutely insane. I nearly killed myself hopping from booth to booth, as there were so many of them.
The PS2 seemed to get the majority of the games, though there were a good number for the Gamecube and Xbox. The stuff for the Gamecube looked absolutely incredible, especially the ludicrously beautiful Luigi's Mansion. Rogue Squadron 2 was also mind-blowing. Over on Xbox, the new Oddworld game looked darn good, as did Halo... and that was about it. The rest of the Xbox stuff (from Microsoft, anyway) was pretty unimpressive.
As to your specifiics:
DOA3 looked pretty darn good. I didn't get a chance to play it, though, so I can't tell you much about the fighting system.
Virtua Fighter 4 wasn't playable, but the Sega guys said that in terms of both story and gameplay it was a lot like VF2, so maybe your dreams have been answered.
As for the Sega booth being private... remember, their Dreamcast is quickly going kaput. The people there told me that Sega wanted to regroup this year and not remind people that they're the owners of a "failed" system. But they'll be a lot bigger next year. Oh my yes.
Xbox online? Who the (bleep) knows. I wouldn't even mess with the Xbox until Microsoft itself learns to make more decent games for the thing.
Myamoto was pretty cool, I went to his conference. He said that when Donkey Kong came out, his parents were disappointed because "now children will play this instead of study." Didn't see Naka... actually I don't know who he is.
Er... this is the first I've heard about Jet Grind Radio 2 for DC, but there wasn't one shown at E3. Maybe they'll surprise us, but it's not looking likely at this point. Jet Set Future (yes, that's what it's called now) for the Xbox looked breathtaking.
New Virtual On? I have no idea. I think there might have been something said about it at IGN, but I'm so tired I can't remember. It wasn't at E3, though.
You read it... you can't un-read it!