I want to yank those little rain gutter deals over the front apillar trim. Do I need to pull the apillar first? It looks like they go underneath it on the bottom

 

I am assuming you mean the curved piece at the front, yes you do.

 

They do go underneath.
You may be able to flex the top of the A pillar covers enough to remove them, but likely you'll have to get the A pillar cover off of it's top and middle clip to move it over enough(there are 3 clips per side, one more at the bottom).
The plastic top corners you're talking about slide on to the metal rain gutter. They need to be pulled straight out towards the front of the truck.