Yes. I have taken mine out to accommodate a bicycle and noticed more road noise at highway speed. I prefer having the parcel shelf in place except when I transport the bicycle.
Slightly, but not dramatically. Also helps with the wumpa wumpa effect a bit (aka Helmholtz resonance), but not totally.
SHELF RUNNER QUESTION- This is a different question regarding the parcel shelf. My 2013 did not have it and I do not remember the rear cargo having the runners. Will someone with an older model that was ordered without the shelf tell me if there are runners?
My 2013 has the runners as well and either the previous owner or Tesla during reconditioning put in the parcel shelf.