UPDATE: I changed 2 pictures of the dragon ball booth, added some pictures of Gokus character costume, added info about the special dragon ball kai event, added info about the map in the dragon ball booth.
First of all some pictures of the dragon ball stand:
The map in the dragon ball booth: All green countries is where Dragon Ball was officially transmitted, countries with a star is where Battle of the Gods has been released or will be released(probably), Pictures showed in the map dont have any special meaning, were chosen at random just to show subtitles in different languages.

About the dragon ball kai event: It lasted for 40 minutes, from 13:00 to 13:40. Masako Nozawa was first invited to the stage, she then talked about dragon ball specially about Goku, Gohan and Goten, after this Norihiro Hayashida; one of the producers of the Majin Buu Arc joined the stage to talk about the picture differences between old dragon ball majin buu arc and this, the process involved that they used, picture quality, before and after pictures and videos, and their intention to make this Arc as faithful to the manga as possible, etc From the 40 minutes this part was the longest, maybe taking 25 min. After this the announcer, Masako Nozawa and Norihiro Hayashida (producer of the Majin Buu Arc). left the stage and Takayoshi Tanimoto appeared to give a live perfomance of Dragon Soul and the new opening song “Kuu-Zen-Zetsu-Go”. It was awesome!
Then Masako Nozawa and the announcer came back to the stage, Masako Nozawa started to use the voice of Goku and said something like this "Hey, I'm Goku! Please watch the new Majin Buu Arc, I am sure you will enjoy it!". Finally they ended the event with the Kamehameha (video below).
(I wanted to embed the videos to this post but I think is not possible)
stand:
http://youtu.be/NPdg7BcERw0
Majin Buu arc promotion:
http://youtu.be/AKHJ-mmsMrA
Masako Nozawa Kamehameha
http://youtu.be/xEqUaguBKeg
Overall I really liked the convention a lot, it was huge!! and there were some very good cosplayers and booth babes!

UPDATE 2
This is from a Japanese site.
The Toei representative I mentioned that appeared on stage was Norihiro Hayashida; one of the producers of the Majin Buu Arc.
He mentioned that its their intention to make this Arc as faithful to the manga as possible, some examples are:
Majin Buu with crossed arms (left arm on top of right) in manga but it was the opposite on the anime:
I have not confirmed these mistakes, I'm lazy to check, and I repeat, i got this from a Japanese site. (my Japanese is far from perfect and that was what I understood, I didnt catch these at the event there was a lot of noise as it was an open stage)
I also got these 2 last images from the same site, I did saw this poster but my camera battery was dead by that time.