Ranks (Warlord, Member, etc) are *not shown* anywhere other than in the Guild Roster. Guild Titles, like we have now, are still customizable, and appear publically as before above your character if you so choose.
Guildstones will no longer be needed.
Current guilds are automatically transfered to the new system. You won't have to reform them.
You can have more than two guilds in an alliance.
The Guild house permission is in addition to the friend, co-owner, etc permissions. They also apply to teleporters, door and anything else that has a permission setting in a house. I will add that to the guide on Monday. (Oops!)

Things I will check on:

Guild name restrictions (why only 20?) and how current guild names will convert.
What happens to current guildstones (do they go away, or just become decorations?)
What happens when a guild wants to join an alliance that is already at war.
Faction guilds allied with non-faction guilds (possible or not?)