If/When the ban expires, can civilians/non LEOs own rifles and magazines stamped LEO only?

Well since that marking is designed to basicly say brand spanking new evil hicap that the masses can't be trusted with I would say yes since when the ban ends there will not be that restriction on evil hi-caps for the surfs, unless of course a new one is put in it's place..

As far as weapons go that are LE only, same thing they just have the evil features so once the ban sunsets, as long as a new one does not come along you can own them in that configuration as well