No these are not really stupid questions. I'll be happy to help as well

1) Check your map and head into these areas You'll be going in a northern direction. The Steeping, Outpost, Yardang Labyrinth, Sand Swept Maze, Banks of Nebra and finally, South Bank Village. I hope this helped.

2) No, the Serpent Skin only gets you an extra item along with the Baraheim key. You'll get the key as long as you do part of the "Sick Man in the Desert" quest. Cuchulain is obtained in another quest involving the Garasmythe waterway...

3) I can't help much with this but try to look at the map carefully. There is two ways to get into that area and usually in this game it involves taking the long way there...