A110: Yes.
The war caster feat does make it easier to cast spells while holding weapons, even though it's already possible to do it under certain circumstances.
In particular, it lets you do it without letting go of your weapon, which can be an issue in cases where an enemy has readied an action to pick it up, or in which the spell effect affects unattended items, or in which the spell causes you to move away from it.
And yes, someone wielding a two-handed weapon is normally considered to be able to free a hand for spellcasting as needed.
Powers &8^]