Some other thoughts:
Other Bonus spells they should have access to: Gust of Wind, Fog Cloud, Sleet Storm, Solid Fog, Ice Storm, Cyclonic Blast.
These are just options to pick from when leveling up that weigh against your limited slots, not free autogrants, so there's no reason not to add a whole bunch of them. I use some of these on a sorc, not sure if I'd ever use them on a stormsinger where SP is so precious but maybe someone would. Options are good right?
Ranged Damage (shortbow support only, maybe) seems more thematically fit to pair with Stormsinger than current WC. Shooting off arrows of lightning and using hurricane-force winds to guide your arrows to devastating effect. Much more synergistic flavor. Maybe some space in stormsinger for these types of bonuses/abilities, and some retooling of WC to work with ranged better (and some retooling of WC in general, cuz it stinks).