Multiple questions. I would like to know for a hackgame I want to do.

I'm not entirely certain what you are looking for here, but it sounds like you want to do some rather extensive hacking to try and make a skill like this. Are you trying to recreate something like the mystic knight skillset from FFV? Sadly I'm not certain how you would go about doing that, although it may not be outside the realm of possibilities.

An easier way would be to prepare a set of skills similar to swdtech that will use different elemental attacks. Of course you will need to remove some of the current magic in the game to add more spells or skills.