Custom NPC / Custom quest

Hello,

I have a few questions.. I want to add a custom NPC as a "Guide" in the game, I wonder if this is possible to just add a normal NPC without tabs and so on, but how do I add the "conversatio" to the npc? Like for e.g. when you click on a quest or similar in a NPC you get a few options, I wonder how this works..

Also is it possible to add new quests, or are you forced to edit Quest.wsc and Questlist.wsc?

Thanks..