Dark is 90 now, Dynamis mobs are a joke to this guy. Only the NMs provide any challenge. In Abyssea, dark with 1 refresh Atma and the rest DD or possibly mounted champion and VV is able to solo normal mobs quite easily. NMs are more of a struggle with dark's speed.

as to spell casting, 1st off, I rarely have spells interrupt my melee attacks on any casting job, including dark. I just pop the macro at the beginning of a swing, and with dark's delay the cast is finished before the next swing comes up. Seems to me lead with Absorb ACC, use your dread spikes when u can, Drain and Aspir 2 as needed. with most stuff going down in a low number of whacks it isn't that much of an issue. As always, if you do have a party, your healers will love you if you at least CONSIDER a bit of defense.