Is there a good overall guide I can read about guilds?Yes. There is one such guide
located here.
How do I create a guild?At level 20+ you can create a guild by talking to any of the Guild NPC's in the towns (Leebaek in Jangan or the two unnamed NPC's in Donwhang and Hotan. You need to pay 500k to start a guild.
How do I leave my guild now?Just go back to one of the guild NPC's listed above, talk to him and select "leave guild" and wallah, no guild.
Side note: You are not able to join another guild until 3 days after leaving the first. You can also request to be kicked from the guild same penalty is applied, but if you're kicked while offline you recieve no penalty.
There's guild NPC's in everytown.
