No, they can't play together. Colonies can play with PC players though.
Can't tell you which version has more activity.
Originally Posted by Creech
As a site, we don't support calling it "xbone" as that was a name that was used to refer to the system in a negative light. Since the site exists to support the system, being deliberately negative towards it seems counter productive.
tl;dr - Call it the Xbox One or X1.