Hello Professor Won Ho,
Thank you for showing interest in MoodleMoot Japan. Kamsa Hamnida!
To answer your questions,
1) Yes, you are welcome to participate in this event and you can present either in Japanese or English language. Please read the presentation types on this page and choose one to fit your needs. The deadline is October the 31st.
2) Yes, you can bring your colleagues as a co-presenter or just a participant.
3) It will be great if we can build up some joint research projects deriving out of the moot. I'm sure there will be people there who share the same interests as yours. Also, Moodle Association of Japan is inviting Sponsors. Any company who is willing to support MAJ is welcome to become our sponsors.
Looking forward to seeing you and your friends in Shizuoka in February.