Just checking if I have this right about getting the following achievements in one playthrough.

If I want the achievements to max both the werewolf and vampire perk trees I have to first do companions, but wait with the last quest.
Play the game until werewolf tree is maxed.
Then play dawnguard and become a Volkihar vampire.
Either cure yoursellf when finnished or stay vampire.

OR if you want to be a werewolf:

Do dawnguard first, max vamp tree.
Cure yourself.
Do companions. With the possibility to cure yourself left open by keeping a glenmori witch head.