3D

3D is supported only with the HTML renderer. It will rely on SVG elements wrapped on DOM elements to be 3d rendered.

Camera

You can use a 3d one-node or two-node Camera.
Camera options are not exportable. The idea of using a camera is to provide a moving point of view for the composition.
You can parent layers to the camera, but you can't parent the camera to any layer. It will probably be supported soon.

Masks and 3d don't go well together on browsers.

So if you mask a layer it will lose its 3d properties. What you can do, is use masks inside 3d comps that have 2d layers.

Scaling and z-axis.

If an element needs to be rendered larger than the original size, it won't be smoothed since browsers promote layers to hardware rendering as textures and they won't redraw them as vectors like the Canvas and SVG renderers do.