ok so first things first , cant seem to transform back to human form after first becoming a vampire lord.... suggestions? and do i need to be bad to be a vampire lord or can i still join dawnguard against them

To revert back to regular form you have to go into your favorites menu (push up or down on d pad) and select revert form, then use powers button (R2 on ps3). And as far as I know once you choose vampire lord you have sided with the vampires. From what I have heard you can decline the offer, side with the Dawngaurd and after the MQ still become a vampire lord.