What exactly are the different levels of effect for a particular Shout....say DISARM. When the first word is learned, how does the shout differ from when the second and third words are learned. The only thing I can tell for sure is that the cooldown time increases with each new word.

Thanks

Depends on the shout. More words will affect the following aspects:

Animal Allegiance: Duration and area of effect.
Aura whisper: Duration.
Become ethereal: Duration.
Call dragon: Must use all three words.
Call of valor: Changes what hero is summoned.
Clear skies: Duration.
Disarm: Target level (cap is only 30 though.)
Dismay: Area of effect.
Dragonrend: Duration. (Note that the cooldown is always shorter than the duration!)
Elemental fury: Amount of haste bestowed.
Fire breath: Damage.
Frost breath: Damage. (Same damage as Fire Breath, but applied over 5 seconds.)
Ice form: Duration.
Kyne's peace: Duration and area of effect.
Marked for death: Damage and armour reduction. (Cooldown is always shorter than the fixed 60s duration!)
Slow time: Duration and amount of slowing.
Storm call: Duration, damage of bolts, and (for three words only) increased area of effect.
Throw voice: Cooldown reduction - always use three words!
FUS RO DAH: In case it's not known, the amount of stagger, and (for three words only) sends stuff flying.
Whirlwind Sprint: Distance covered.

Wow. Thanks!!!

I always assumed it had a range aspect, too.

Indeed, long range is long. From the bottom of a room to the top of a balcony.

I thought so because I ham-fist my PS3 controller every now and then (they're so damn small - Japanese and their tiny doll hands ) setting off only one word and the blue 'burst' is much closer than when I use all 3.

I haven't looked at it in the CK, but it is obvious that range is a mechanic of it.

Although, personally it becomes obsolete after sometime when you have significant sneak levels, it garners lots of lulz.

Pretty much. I still use it, though. I like making groups of mobs go by me then taking out the one bringing up the rear, moving and taking out the next one bringing up the rear after they start heading back to their scripted areas/patrols.

I never use any shouts except Dragonrend and Whirlwind sprint. Rest are just useless.

I just realized the other day, that dragon souls are required to upgrade the shout.

For the longest time, I just assumed that once you unlocked the shout and found the word, that each additional word would upgrade on it's own... not so much haha.

Yeah, I ran around for a while too until someone told me I had to unlock them. It's not made very clear.