How can we do extra quests? I've heard people talking about it but don't know how to do extra quests.

As you go about the site, you may get a random event telling you that you can do an extra quest.

But you only get the extra quest if you've already done, or mostly done the rest of the quests because its time limited and very short duration.

yeah, I think it's like a 4 minute time limit for the buff, or close to it. Maybe 5?