The tutorial mentioned that the Empire team's Power Relays operated by Line of Sight. Does that mean that so long as there isn't anything between the two relays, I can make them any distance apart from each other? Does that mean that the structures that team makes have to be in sight too, or just in range of a Relay?
Empire relays do have a limited range, however, it is much longer than that of the Consortium relays.
Power can in some cases be routed through glass and some other transparent surfaces. IIRC other buildings you construct are ignored for line of sight.