hmm, that didn't quite work for me. Not sure why as I've done exactly what you did. However when I import my z .iff sequence into fcheck it only imports one image rather than the whole sequence. And this image seems to have no information in it at all. After effects tells me that it is an unsupported file format...
Anyway, since I didn't get it to work my experience is only theoretical. Yo will need after effects pro to do anything with the z channel. Under effects you will find 3d channel and various options. Like 3d channel extract which I think allows you to split your layer and have other layers slide into your 3d images at various depths.
You can also apply depth of field, fog etc. AEF basically uses the black and white image as a matte to apply effects.