Ok so i heard before, that the people in the College of Winterhold will not attack you, even if your on stage 4. Is this true?

And also, i know that vampire seduction causes an enemy to not attack you for 30 sec.....but if used on a shop owner, could you buy/sell stuff from him during the time limit of the power?

I am on my 6th char. It is the second playing as a S4V-24/7. Almost any NPC will attack you on sight. There are very few exceptions. Even the college. That is until you become a member. Once you become a member of any faction, they will accept you at S4 without you having to charm them. The same applies to shopkeepers and other NPCs once you complete a favor for them. (ie their personal quest) But if you ever feed and then reach S4 again they will be hostile. Since you have already triggered their friendship by joining the faction or doing their quest. There is nothing else you can do.

You can play the entire game as a S4 Vamp, by using the Charm, Pacify and Harmony spells. This will allow you to engage dialog with any NPC to trade with or advance / obtain quests. I find this type of play to be very entertaining and strategically challenging. Once they have befriended you they will fight for you to the death. Even against guards and other hostile NPCs. This leads to some unexpected and humorous events.

That was a very informative post. Almost want to start a new altmer mage vampire. I do not know if I could deal with the hastle of having to recast the pacify spells in a town.

I have a question; how does a stage 4 vampire deal with enemy fire attacks?

Ever since I was cured by that priest, I haven't faced any vampires anymore, and have no chance of becoming one again.

As an S4 you should be very very sneaky while moving around town. It demands a high sneak skill and a lot of use from the Invisibility spell. As far as fire...don't get hit. The best defense against it, is avoidance. You can play as a Dunmer. They have 50% resistance. Add in some enchanted gear with a total of 50% and you have negated the added effects of fire. I like to keep the 100% extra damage because they need to be very very afraid of it. If I negate the effect, it kind of defeats the purpose of being a Vamp. Granted you can walk around in broad daylight, but still...

I like to play as an Imperial. They have the calm AOE power, The Voice Of The Emperor. I try to become a Vamp as soon as possible. Before going into Riverwood for the first time. I like to play at S4 from the very start. TVOTE power comes in very handy, even at later levels prior to getting the master level spells. However it is listed as calming anyone, not creatures, to level 99. I have found that this does not hold true to some NPCs. I can only assune that this is a bug.

EDIT :

You have no chance or you have no intentions of becoming one again? Although I have not tested this, I was under the impression that you could still become a Vamp again, even after being cured.

On a side note...Due to being a spoiler, I will not reveal the name, but the effect of a certain piece of armor will turn you black and emit a black smokey like aura, when you crouch into sneak mode. Turning invisible will still emit the smokey aura. This is very Vampire like, I must say. You basically are moving around the game as this eerie black smoke hovering above the ground. Then you execute a stealth assassination attack and the kill cam is epic.