This is pretty fantastic. I think the iterative attacks should just be a class feature once the character reaches BAB of 6/1 and always thought it was stupid that it wasn't in the first place. As for blast shapes/effects. You can either:
a) allow it to only apply to the first attack or
b) make it so that it only applies if you don't use iterative attacks or
c) make shapes able to apply to all attacks but not effects.
I think the third option is better and also see no reason for making a single attack over multiple better.