Quick Question:

How would ih208 General Thunderbolt Ross' 'Call In The Airstrike' power affect Colossal-Sized Characters? Since the power specifies other characters would the spill-over damage be a moot issue, or would this be a way to affect the colossal multiple times since they occupy multiple adjacent squares?

No. You're going to decide if the character is hit and how much damage they take based on where that character is, but you can only hit each character once.