Dear ShadowThunder,
My experience is that you must earn Gcw each week to advance in faction rank.
Also, once you reach a certain high lvl rank (Officer or higher I believe), you must maintain that rank by earning more Gcw each week, or else lose your rank. (The rank degrades, they did this so that you wouldn't have 2000 generals running around at once)
As for Faction points, I don't know how important those are...Storm troopers attacked me the first day I went pvp as a rebel, before I had lost any empire faction, or gained any rebel faction.(I think faction matters more with non-Gcw involved npc's like Jaba faction, and whether or not they attack on site)
I do know that you can check the bazaar, and find "commendations" that you can buy and then use those to gain access to special equiptment at your respective bases.
Sincerely,
SouleSurvivor
Jedi Knight
Rebel Ace Pilot
(Former Sith)...lol