Well let's go by parts, on single Target dark arts is better to use on carve and spit, shyphon, soul eater,plunge and bloodspiller, all of then get 140 potency except carve and spit since gain 350 of potency, So yes carve and spit always with DA on single target (on mass pulling carve and spit to gain extra mp is better).
About delirium, always with blood weapon on single target, you notice blood weapon is only out of grit so the deal is pull with grit, generate a lot of agro and then turn off grit to push dps and use you mitigation kit properly to compensate, if you feel you can't manage that or you healer can't keep you up then turn grit on but the ideal is every delirium with blood weapon, if not then yeah with Blood price, but never alone.
About bloodspiller, use it all the time you have 50 blood, the skill don't broke you combo so you can use it any time you want, except you have to use delirium then save some for it and never overflow blood.
On mass pulling, use unmend and unleash to grab and place all the adds and then when you have it all stack spam abyssal on then, use DA with abyssal to some nice self heals if you need it, when you have all the skills the thing will be use the blackest night to gain blood, use quietus to gain mp since you get a nice Chung with every Target and use that mp for more TBN and AD, delirium work well with blood price in Mass pulling so you can use it there.
About dark passenger is a dps gain with 2 or more targets only, it can be used single target if slashing debuff is no present ( that's why we use it on the opener) it's nice use it in Mass pulling but whatch you mp, DA dark passenger is nice but cost a lot, don't run out of mp and get defendless.
And your openers the mass pulling is good, and the single target is not ideal but is decent if you are not going to turn grit off, just use dark arts before pull so plunge bring you extra agro at the beginning.