Was toying with trying to make a Vampire character, but I don't see a lot of upside. Does that limit what quests you can do and who you can talk to as far as being around people? How did you manage to get Vampirism? Don't they try to kill you? Give me some insight.

Doing Dawnguard on the Vampire side is the quickest and most convenient road to vampirism. It doesn't stop you from doing any quests other than the good guys side of that DLC of course.

If you don't got DG, just let vampires hit you with their special magic attack and you have a chance of getting infection. Don't cure it for 3 days and you become a vampire.

If you have Dawnguard then people won't attack you for being a vampire.
if you do not have Dawnguard and you reach stage 4 vampirism then you will be attacked on sight by most or all NPCs.

To get the most out of a Vamp character, you really need to be on PC.

There are some awesome mods for Vampires.

I play as both vampire and werewolf but to answer your question it depends on if you have the Dawnguard DLC

If you have it then stage four vamps will not be attacked (you will be attacked if you use the vampire lord power which is similar to being a werewolf but without the time limit)

Without dawnguard . . . yes they attack you if you go stage 4 vampire.

I didn't know it mattered, but I don't have Dawnguard. Can you be a Vampire without going to Stage IV?

Yes, if you feed on people before you get to that point, just make sure they are sleeping, a sleeping spouse for example, or even Aerin if he ever goes to sleep and you are married to Mjoll (on a side note I find it hilarious how he suddenly appeared on Solstheim and started speaking as if he were still in Riften)

Vampirism boosts illusion spell potency by 25% and your sneak by 25%. And you'll have night vision - which I love. At stage four you acquire a greater power that gives you night vision combined with invisibility once a day.

You can't complete the Dark Brotherhood quest line as a vamp due to a bug in one of the quests where an NPC won't talk to you. You'll have to cure/reacquire to get past the bug. (Note: I play the original unpatched game and I don't know if this bug was fixed in a patch.)

Which NPC would that be, also that might be pre dawnguard as well so . . .

Playing as a vamp for me really is no different other than the penalties against your health magika and stamina regen when out in the day. But you can always enchant items to negate that.

The "Better Vampires" mod for PC is a must have for your vampire character. You get vampire "level progression" based upon how many times you have fed and it unlocks some truly awesome powers. I love timed blocking attacks from enemies then swiftly darting behind them during their stagger and feeding on them. Vampire Power!

well vampire lord has it's own level up system so there's a benefit to using it