For missing mask in Safari browser, please anim.setLocationHref(locationHref) before animation is generated. It usually caused by usage of base tag in html. (see above for description of setLocationHref)
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.
So if you mask a layer it will lose it’s 3d properties. What you can do, is use masks inside 3d comps that have 2d layers.
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.