I have a need to produce HD p-video at 24 fps. Using masks, etc., I want to layer over a video a spinning/exploding/etc photo real 3D model. The person video'd would be explaining/pointing as to what's going on, apparently in real time. Is After Effects the correct tool for accomplishing this? If not, which other one in CS5 Pro? When inserting the 3D model video, must it be at the same frame rate (24 fps) as the video? Is there a tutorial/FAQ/etc for constructing this scenario?
Layering videos over one another is called compositing and is exactly what After Effects was intended for. It's not something you can just jump right into though. AE is very broad and very deep. I highly suggest you start here first: http://blogs.adobe.com/toddkopriva/2010/01/getting-started-with-after-eff.html
The (free!) resources linked there will get you started on the basics of AE.
Thanks, exactly what I was asking for.