[@Wanderer of Philosophy] On primed staffs/wands: Yes, that's possible, however that would severely limit it's already limited use - still, depending on the situation, it's not uncommon to have a staff primed with a spell already. 

On how much you can command; generally, command and skill come with practice. To specify on the mechanics of chanting, it's a mnemonic; the words themselves follow a specific kind of alphabet that actually changes depending on location; the original alphabet for the present time spells were based on star patterns, and as the position of some stars varied and appeared for those locations, localized alphabets for chants were created - basically, there is no unified chanting system, and spells that work in one place might not work in another.

However, chanting is not the by-all-end-all when making a spell - it is still up to the caster to create its composition and direct its purpose. Knowing more of the alphabet (I will have to place a chart for this soon O[sub]3[/sub]O ~) will simply make your control more efficient, as longer and more detailed chants become available to you.

[@Zeroth] Magestrava and Sepcarim are mutations in the population. The mutation is what allows them to be able to manipulate energy - basically, if you're not born one, then you can't be one.