I have pretty limited knowledge myself so I wouldn’t mind hearing from someone with more experience but I’ll share what I can with you.
I’ve picked up 2 WFR traits and for me it seems that using thrash gives a boost to my DPS on single target so yes I would imagine even with 1 trait it would be worth you using thrash. Your opener looks the same as mine so from the perspective (unless someone comes on and tells us different ) I think it is right.
Even with only 1 WF, you should be using thrash to keep up your dot on main target. Due to Shred/Brutal Slash dealing increased dmg because of the Trait.
Yes, you should be using trash after your initial opener, to gain as much dmg as possible with the WF Trait. Just never use bloodtalons proc on trash, as you’re not trashing for the dot.