Magic Wands

I am starting to work on the biggest mod I've ever created, themed around pretty much anything magic.  The first thing I want to approach is wands/staffs, one of the biggest parts of the mod.  I just don't know exactly how to approach them.  All I know is I want the different kinds of woods to be more compatible with certain types of magic, and that different gems you put on the wands change the type of magic you can use.  The options are:

control over water (summoning rain and give a portable infinite water source).  Is it possible to make it rain even in rainless biomes?  Also I was hoping to find a way to let water be in the nether.  

control over death (like summoning skeletons or zombies that fight hostile mobs).  How can I find places they can spawn and where they can't?  I don't want them spawning inside blocks or in the middle of the air.  

control over fire (like explosions and ghast fireballs).  I just need advice on how big the explosions should be.

control over plants (like infinite bonemeal or summoning any kind of plant).  I don't know how to do the bonemeal thing.  Is there a way to trigger bonemeal on a block or something?

control over earth (something that can let you mine large areas quickly).  No problems.

control over electricity (strike lightning and summon thunderstorms).  This one seems pretty easy except that I don't know how to follow the gaze of the player to detect where to strike the lightning.  

any answers to any of these questions are welcome.  I would have done all of these in seperate topics, but I don't want to clutter the forums for no reason over similar topics.