So I turned level 17 inside that simulation. Now I'm ready to acess the VSS armory.

However, I have not completed the ''you gotta shoot them in the head'' mission.

I'd like to complete it before entering the VSS armory because it will auto complete it if I do and I think I'll be missing something good in the campaign.


I have a savegame in front of the VSS armory door. Can I just exit the Outpost and do this mission right away then come back to complete opration anchorage by entring the VSS armory ?


:)

You Gotta Shoot Em In The Head will only auto complete if you pick up the power armor in the armory.
So feel free to enter the armory. Just leave the power armor alone for the time being (you can always come back for it later) and you'll still be able to do the quest.

Is there a specific order to do the DLC to avoid this kind of situation again ?

No, it's just that the game doesn't seem able to tell the difference between the Winterized T-51b power armor from the OA armory and the T-51b power armor that's part of You Gotta Shoot Em In The Head. As soon as you pick up either one the quest gets completed.
There's no way around this other than doing the quest first, or leaving the power armor in the armory until you have finished the quest.
Or you can do OA before you pick up the quest, take out the power armor and store it somewhere. When the armor gets into your inventory while on the quest is when things go bad.

Does the unofficial patch fix this/