some questions about chrono cross

hi guys, i finished chrono cross yesterday, and after reading quite a few plot summaries and analysis, there're a few things i just don't understand:

1)so basically everything that happens in the game is actually balthazar's plan to save his friend schala, right?
iirc, even the whole thing about schala hearing serge's crying after he was attacked by the panther was balthazar's doing.
so the question is, why serge out of all people?
before serge became the arbiter, there was absolutely nothing special about him, why did balthazar choose him for his plan?
how did he even know who he was?
(note: if my memory is mistaken, and schala's creation of the storm that led to serge's becoming the arbiter was NOT influenced by balthazar, then my question was answered)

2)in the very beginning of the game, when the huge wave washes over serge and sends him to the other world.
who does this to him? and how did he do it?

3)where is lady riddel of the homeworld? we only ever anotherworld's riddel.

thanks

Well, thanks. Now I don't have to finish the game. lol

Which way did you complete it? Because there are apparently several ways (or maybe just two) to beat the final boss or several ways the ending can change due to Game+.

1) Serge is chosen because when he was dying from the Panther poison, his voice reached Schala and woke part of her, Balthazar saw this while studying the parallel time streams and it helped him be able to formulate his plan. Regretfully I can't remember who caused the storm but I do believe it was Schala actually, trying to reach Serge unconsciously.

2) FATE did this so it could bring Serge into Another World and gain the means to unlock the Frozen Flame from him, by switching bodies with him.

3. She went with he expedition that went to explore the Dead Sea and was frozen over in the eliminated time, with the rest of the Dragoons and General Viper. You see her among the group when you first enter the place.