Maintenance for the week of January 19:
• PC/Mac: No maintenance – January 19
• NA megaservers for patch maintenance – January 21, 4:00AM EST (9:00 UTC) - 10:00AM EST (15:00 UTC)
• EU megaservers for patch maintenance – January 21, 9:00 UTC (4:00AM EST) - 15:00 UTC (10:00AM EST)
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.