Maintenance for the week of January 5:
• PC/Mac: No maintenance – January 5
• NA megaservers for maintenance – January 7, 4:00AM EST (9:00 UTC) - 10:00AM EST (15:00 UTC)
• EU megaservers for maintenance – January 7, 4:00AM EST (9:00 UTC) - 10:00AM EST (15:00 UTC)
Guilds can be cross faction, however when the guild is created you still need to designate a main faction and while I am not sure entirely what this choice dictates, I do believe that it affects claiming resources in pvp but this is speculation as I haven't tested it. Also, while you can have people from other alliances in your guild it will still not allow to group with them in dungeons or pvp.