When casting a spell, the spellcaster speaks an incantation (verbal), performs an arcane movement with his hands (somatic), but does not use a material component unless the spell explicitly calls it out (material).
This means that for a spellcaster to cast, they must both be able to speak and be able to move both their hands.
At the end of adventures (not necessarily sessions), Karma is awarded to the players. The first 9 points of Karma awarded are Good Karma. The 10th point of Karma awarded is not Good Karma and is instead added to the character's Karma Pool.