Just wait for dawnguard? I play on making a vampire slayer, will making a new character now hinder my playthrough for dawnguard?

I did the same , started over with a old save and made my guy a vampire

I'd much prefer to head into the DLC as financially well-to-do, well equipped and armoured, and with an already developed character than trying to tackle all the loft goals of blotting out the sun with a level 2. Call me old-fashioned, eh?

Well Todd Howard said the content is generally intended for level 10 and higher, so you could certainly start your character and build up your archery skills to make good use of that crossbow, if you're still planning on making a vampire slayer. I don't think it will hinder your Dawnguard playthrough at all, it doesnt take that long to get to level 10.

if my character becomes a werewolf now will it still benefit from the werewolf perk tree?

I started a new character very recently, whom I will probably run through Dawnguard. But I understand the desire to start a new character. Starting a new character isn't about playing through the DLC at low level - it is about playing in a consistent game world in which the DLC content already exists. So instead of new areas/people/etc. being added to your game, you are playing through the game with them being there all along. For me, it is a more immersive experience. Personally, I'm hoping I don't get too far with my new character before the DLC comes out. I don't want to feel like the game is already complete and then Dawnguard is the next chapter - I want it to feel like something that exists in a wider world.

i started a new char because i wasn't happy with my perks.