OK, here we go;
A complete list; not that i know of, you can however compile one that is about 70-80% complete from all the faqs on
http://www.gamefaqs.com the reason there is no 100% complete list...freelance quests theres umm a lot of them i dont think anyones ever done all of them. this probably has something to do with all those stupid escort quests where the NPC moves at the speed of a stuned snail and constantly gets inbetween a creature and your DDK.
As for the werewolf ring, and being a werewolf.
Its like this you become a werewolf and you do the werewolf quest or you dont and you do the skaal's quests pick one.
Also you cant be a member of more then one great house and if your kicked out of one you cant join another so pick one that suites your personality/playstyle and stick with it.
Vampire Quests: there are 3 vampire clans, you can only belong to one of them, Fininshing the vampire quests removes you of their curse
also vampire/morag tong/fighters guild quests could potentialy break other quests but i havent tested this.