>> If they can get Shiv interested in geometry, and especially topology, he could have a *lot* of fun with his abilities. <<

I think so too.

>> I'm suddenly picturing him creating really thin sheet metal 3D graphs of functions. <<

He could, yes. It's a matter of building up from the skills he has.

>> I really do think that if he can get the idea of how equations relate to shapes, he might be *really* good at visualizing things.<<

He is. The equations will help, but if you can show him a shape, he can figure it out.

>> Wonder if he'd turn out to be one of those folks that can "see" 4d shapes.<<

I think so. If he keeps hanging out with the Finns, he'll probably wind up fidgeting with a wire-frame tesseract.