Getting Started with 3D in Flash

I posted this question a couple days ago, but for the life of me I can't find it anywhere.

I want to get started creating some 3d flash sites. I've heard about some of the programs being used: Adobe dimensions, lightwave, 3d studio max, maya. But I don't really know how these products compare in features, power, price, etc. If I'm going to do this, I want to do it right, you know? So I guess if somebody could give me some pointers in getting off in the right direction in creating 3d flash sites, I'd be really grateful.

Also, I don't really know how 3d flash is done. do you have to render scenes in the 3d modeling program, and then just import them as frames into your flash movie? seems like this would lend itself to creating pretty huge flash scenes.

thanks! -tim