I get on the boat for Moonshade and nothing happens.
There are three other people who must get on the boat with you: Hawk, Kane and Flindo. Make sure that they are not asleep or dead.
I'm stuck on Moonshade! How do I get off?
After the banquet, go to the Blue Boar Inn at 10 pm and talk to Bucia about Pothos. Bucia will say that Pothos looks a lot like the Mad Mage, and that they may be related. Go to Pothos and tell him you know his secret. If you bring him some Blood Moss he will tell you how to get to Mad Mage Island.
Why can't I get into Skullcrusher?
If you've fulfilled the quest for the Gwani, they can tell you how to get into Skullcrusher. Put Batlin's Amulet (which you should have gotten from Shamino's Castle) on the ground and have the Hound of Doskar track it. Then talk to Yenani and ask her about Skullcrusher. She will give you the password. Note: It is possible to deduce the password, but the door will not open until Yenani actually tells you what it is.
What am I supposed to do with all this water?
These waters (there should be 6) will allow you to free your companions from the Banes. The waters of Enthusiasm, Emotion and Tolerance should be used on the soul prisms to prepare them to hold the Banes. Once the Banes have been trapped, use the water of Ethicality on Shamino, Logic on Iolo, and Discipline on Dupre to make them sane again. See the walkthrough for more info.
Where can I get more Serpent Teeth?
You get Serpent Teeth as the plot advances. There really is no way to get teeth "ahead of time". You should have 18 teeth by the end of the game