Some questions on assassination pvp


What is the optimal opener? Does it vary clothy to plate?

Is subterfuge the best way to go?

Should rupture only be applied at 5 points? Does assass forget about rupture if opened with garrote?

Use offensive CDs separate or stack them?

Stuns on DR, vanish on CD. Will this mean I have to use evasion and cloak of shadows offensively to keep up the damage? Since its a sustained damage spec...

Also some tips against warriors and warlocks thanks