Animated short

I’m working on an animated short, and I’ve got some questions.

What’s best: rendering in Cycles or internal, for an animation?
I know that cycles is more accurate, but can take longer.
What are the pitfalls of cycles?
What are the things you can run in to, that could give problems when I would make the animation in Cycles?

I’ve got another question regarding the high poly mesh for character animation.
Is it better to use displacement maps or Normal maps, and why?
I get the impression that in the game industry normal maps are often used, but because the silhoutte is important in animation, would a displacement map be better?