A while back I sent out an email to Keith Lango, now an animator at Valve. He was kind enough to get back to me with this advice.
For a younger student I would always suggest they work on their mechanics- getting the motion to look right. You can work on acting along the way, but at this point I'd put it second. Animation, like any form of artistic expression, is a two sided coin. There's the art side- what do you want to say and how do you want to say it? Then there's the craft side- the technical skill needed to express the art in a manner that is clear and understandable. Acting is the art side, mechanics are the craft side. You can have the greatest idea in the world but if your mechanics and craft are not well developed you will have a difficult time finding success in expressing that great idea in a way that the audience can connect with. I hope that made sense. :> Any collge or university you go to will usually have a much broader program of instruction than just character animation. Sheridan is a fine school and has some really good teachers and faculty. You will be exposed to more than just animation. You'll get color, design, composition, lighting, 2d animation, life drawing skills- all stuff that I think is important to learn. I never went to college for animation, so those are all things I have had to learn on my own over the years. If I had a chance to go back and do it all over again I'd try and get into an animation/art/film school first. There's so much to be learned there. AM is just animation, so if you're absolutely certain that's all you want to do then AM makes sense financially. But I actually think Andrew makes a lot of sense when he suggests a traditional art school and then AM. In the end I am always a believer that the broader your range of understanding and experience the better you'll be as an animator. Too tight a focus leads to a shallow view of film and art. There are so many things I've been able to experience in my career that were beyond just animating and each one was cool in it's own.
As for getting to the big studios, just keep practicing and making animation. Eventually if that's your goal you will get there.
I have a few emails like this which I'll definitely start to post.