I agree with some parts, I disagree with others.
1) STS + DV , double DV , STS+WFS. You could even go STS+dbw since your wfs is on normal. Stay away from Herkumi/Taij for pvp, both are complete garbage. Don't be scared of armor penetration, some of your bis items have armor penetration anyway (PP belt, marrow boots).
2) 1.8+1.4, don't go double 1.8. Heaven's Fall/1.8 WF dagger in main hand, Lungbreaker/1.4 WF dagger in offhand. Up to you.
3) 1k+ resil in 2's/bg's/wpvp, 1150+ in 3's and soloq. Most of your gems should be resil for yellow+blue, ap+resil for red
4) Your talents are bad, the linked talents from the above poster are also mediocre. Glyph of Envenom is a waste of a glyph slot (not a great one, but still, sprint/CoS/tott/Vigor are all decent for the 3rd slot) not to mention the 3% damage and reduced poison damage on yourself that you're skipping. Bloodspatter, however, is viable and does a fairly decent job against the amount of platers doing PvP.
Tuskar's Vitality does not provide the same amount of movement speed as Sure Footed. If you don't like Sure Footed go for Quick Recovery, or if you plan on playing a lot solo you can even fetch improved kidney. Quick Recovery is also great against classes that dodge a lot, like ferals or hunters. I also don't see the point in going 5/5 in Deadliness instead of picking up Find Weakness instead, which point for point is a stronger talent. I'm fairly certain that Lethality is also better than Deadliness.
Also in the talents linked ifhf I don't see the point of 3/3 in Initiative. You won't be restealthing as often as a sub, you do a bit more tunneling. Focused Attacks is also not the best talent around. This would be my suggestion with Blood Spatter since you want to play that:
https://wotlk.evowow.com/?talent#f0e...cuZ0hZebfbh0zb
These talents are somewhat customized for your playstyle. I personally play 3/3 Deadened Nerves instead of 3/3 Find Weakness since I'm mostly playing soloq and I'm playing Sure Footed just for some easier kiting.
The talents you can play around depending on your playstyle are (for the most part):
Currently in the talent tree (not necessarily maxed out): Lethality, Improved Poisons, Quick Recovery, Murder, Find Weakness, Dual Wield Specialization, Master of Deception
Not in the talent tree: Sure Footed, Deadened Nerves, Focused Attacks, Setup, Heightened Sense, Initiative
If you want to lurk around wpvp, fetch Heightened Sense as well and just drop some damage from somewhere (1 point from lethality, 1 from DW specialization and 1 from FW for example). If you want to just kill somebody in a kidney, drop Master of Deception and get some extra damage. The talents above are interchangeable, everything else is pretty much mandatory. Hope this post helps.