So my spiders will hurt marines on a 4+...
That's a bit of a nut punch for them
I don't think so. It still says the weapon is S6, on further glancing through those rules--vs Marine typical I4 (to represent T4), that'll be wounding on 2+.
Good stuff. Did any of their transports get the assault vehicle rule? (Hoping NOT )
Nothing in the rules says anything about that, and I think there'd be a buzz if it did, but... Dark Eldar can't buy dedicated transports as, say, FA slots, yet, can they? I imagine they will next codex, so you'll see Banshees in Raiders/Venoms, and such...