What are you talking about? They were instrumental in helping Starbuck realise how to find Earth.
In a sense. I wouldn't ever call them useful, important or powerful, though. There's absolutely no differentiating them from humans, and it really better be expanded in the next 'season'.
I'd say that what makes them special isn't their power or usefulness, but rather that they are so human. BSG is obviously a story about xenophobia, and I'm betting they are the ones that will make everyone, both human and cylon, start doubting their own prejudices.
Isaac Asimov would be proud.