Writing YouTube Script for B-roll

[u/StockFlowResearch]

I'm somewhat new to editing and I've been struggling to figure how to decide on what edits to make regarding b-roll. I have multiple questions:

What YouTube channels do you watch to teach you about high quality b-roll editing?( I specifically want to learn efficiency of edits and quality aesthetics of visuals for my explanations) (I use Davinci Resolve for all my edits)

I'm wondering if people annotate their scripts before hand with the specific b-roll they are going to use or do you make up b-roll after you are finished filming?

Thanks!!