Should one tighten valve cover bolts in a pattern?
 

Sorry, this seems like such a simple question, but I thought the manual called for a pattern sequence, just like on head bolts. I can find no mention of it in my manual. 15Nm is the torque, but seems to me there should be a sequence, albeit an easy one.

Isn't it just wise to always use a 'star' pattern, or alternate to ensure even pressure?

I do. but as long as the gasket is on securely, and the cover is seated evenly and nothing is stuck under the gasket. it'll be fine. (assuming you used a new gasket)

i go diagonally.

I usually criss-cross my pattern. And I usually tighten one some then the next, and work them down until they are tight. It may not be necessary but it can't hurt. I do the same with oil pans and the like. Maybe not criss-crossing but a work them all down at the same time, not tighten one all the way then go to the next.

First, are you gluing the gasket to the removable part.. the valve cover in this case... with ' yellow death' after cleaning it so you could eat off it ?

Yep that's what I do too! Softly softly can't hurt!