Just curious is all, also can circlets be worn with hoods on?

Circlets count as a head item, as do hoods, so you cannot wear them both. As for the Dragon Preist masks (which are actually hooded if you put them on), they should say weather or not they count as armor. I have two of them so far, Krosis and Nahkriin. Krosis is light armor while Nahkriin is heavy armor. To see what they are, highlight them in the inventory screen, and it should say above the item title in the details box. I don't have any that don't say anything, but I imagine there may be some that don't, which would indicate a mage item... then again, they may all count as something, becasue the Nahkriin one is a pretty good mage booster, and it counts as heavy armor... so yeah. Anyway!!! Just look at the item details and it should tell you what it counts as.

That one is special...... It might not be armor because it really isn't meant to be used all the time like the other masks. It has a special purpose... and now I shut up to avoid spoilers.

The wooden priest mask counts as light armour, so yes it's armour