at the same time vampires attacked me as well

Yeah, random stuff like that can and does happen from time to time. Don't let your guard down.

I believe Dawnguard added random werewolf attacks?

yeah, feral werewolves were added with Dawnguard to nighttime

Yup

I dont know what it is with my game but I never ever get Vampire attacks nor have i seen any feral werewolves. Even on my higher level characters its like there is no Vampire menace at all. Only very rarely to I see a attack and on some characters they never witness one.

is their a chance to get the lycan deisese

I would think so , I mean why would they put them in the game and have them sterile so to say. I assume that the introduction of Feral Werewolves is so if you dont want to join the Companions you have another way to get Lycanthropy.

They say if you go out at night sometimes you will see a werewolf and a vampire fighting.