I'd open the PDF in Illustrator, which will do two things: first, you can segregate items in the PDF into separate Illustrator layers or eliminate them entirely, which is good for animation in AE. Second, you can turn it into an RGB document, which is a lot more versatile for use in AE.
As Dave said, you will have to open the PDF in Illustrator and organize the individual elements to separate layers. Otherwise aE only sees the whole page without being able to extract the individual elements.
Inside Illustrator you should group the elements you want to animate and then release them to layers using the tools inside the layer palette in AI. If you can't figure out how to do that just create a bunch of new layers, select the elements in AI you want to animate and drag the little colored dot that appears in the layer palette to a new layer.
Open as a comp maintaining layer size and animate away.
Thank you guys.