Instead of trying to complete certain quests, if you don't know in advance where you need to go, try just exploring specific areas. Check your quest log and only worry about finishing off particular side quests when you are pretty much finished and need to move on with the main plot quests.
What is your problem with Amdusias? You need to turn him human before you can defeat him. After that, AFAIK level 16 should be enough...
If you attack him with melee weapons he will switch away from his bow, and not be able to use Exploding Arrows on you, if that is the problem.
Help on Killing Amdusias. Any tips would be nice. - D2:ED topic, but it should still be applicable to DKS
BTW when you do finish off Amdusias you will get access to Sentinel Island. Your first encounter there you can mindread to go up a level, so the higher level you are (in D2:ED I made it to level 18 in the fjords) the more of an experience bonus that will be. You don't need to get to a high level, but it would be better if you got to a new level before entering, to get a full level bonus.
