There are several types of quests. Some quests are unique and can only be completed by a single player (e.g. the Caliber quest in ALO). Other quests reappear periodically (e.g. ogre slaughter quest on the 30th floor). Some quests are instanced (e.g. floor 3-10 campaign quest). For more information, I recommend reading our Quest article.
And as for the Pneuma flower, I don't think that that's even a quest.
If you have any questions about the things you watch, I highly recommend reading through our articles (though be careful about spoilers), as they are based on the novel, not anime, thus they have more information than the anime has given. And if I were you, I wouldn't trust the translations of the dub that much. The translators were lazy to do their research and have made numerous facepalm worthy mistakes.
That's why we have a wiki. It's a collection of information about each subject from all the novels in one place. Much easier to look up.
Oh, and if you haven't read the first novels, note that the anime changed quite a few things from the novel in the first arc, so I do still recommend reading them at some point.
It happens. Anyway, if you have any questions, feel free to ask them. Not all the known information is present on articles, since there isn't always a good place to put them or just people are too lazy to add new information and one or two active editors are just not enough to handle all of it.
can someone do the "shipwright of yore" quest page. it would be quite easy, but i am terrible at stuff like this, just wrapping stuff up.