1. Bloodthirst. it procs every thing, Blood surge, enrage, your mastery, Raging Blow.
2. Blood surge procs should be used ASAP after the BT that procced them, and ideally Back to back to not delay the next BT or stall the GCD cycle. Otherwise don't use WS outside of CS or trinket procs.
4. Use them to fil empty GCDs
5. pretty much on CD