You must finish the quest, and believe me its a bit worth it cuz the count gives you 2500. To be able to go out in the sun as a vampire you must feed and to feed go to someone sleeping and crouch click a and it should have two buttons feed or pickpocket and obviously pick feed.
Second, when you become a vampire there are stages of vampirism, when you go through many days without feeding you will have full blown vampirism which adds a bunch of points to your strength attribute.
Third, in the oblivion gates with three towers you can either go straight to the central tower, and climb all the way up and get the sigil stone just like the kvatch gate(if there is no gate in the way of the entrance). or you can travel up one of the outer towers and climb up, along the way you will see a door marked wastes of oblivion or something like that, remember where that is and then keep traveling up until you come across a wheel lever activate it and it should expand the bridge. Then go back down to the wastes of oblivion door and go through that, and you should come out on the bridge so you can walk to the central tower. Any questions
