Event Hacking question

I'm wondering how hard/complicated would it be to remove the Opera scene and replace it with an event that gets you setzer and the airship in another way.

Also how hard or is it possible to have you get two characters at the same time when you get the airship. In other words Setzer and one other. Is that event stuff still or is that ASM stuff.

I am VERY new to event and asm stuff, and trying to guage if my ideas are too big for my britches.

Thanks in advance to all the pros with this knowledge!