Famitsu PS2 "FINAL FANTASY VII ADVENT CHILDREN preface" hot news report
Concerning various puzzles we have a direct hit from the staff!
"As for older brother mentioned?": Is the older brother Sephiroth?
Nomura: What kind of connection is there between these siblings [Kionae says: I'm not really sure about the siblings part...], and Sephiroth? Who are they pointing to, calling older brother? That is something I'm going to let you look forward to [Kionae says: Interpret that as 'I'm not telling!']!"
"Three youths": These three people seem to have much in common, but it likely that they are siblings?
Nomura: Yes, it is so. They could also be called Advent Children.
As for the reason they attack Cloud....
Nomura: What? Perhaps they just don't like him.
Kadaj: He can be calm, atrocious and immature, intellectual. His state of mind is extreme.
Yazuu: He is very aloof. He is a man of few words, and does what he pleases.
Loz: You can see a difference in his eyes. He is immature and has a short temper.