a) Because David, like the majority of other OVW/HWA/developmental talent, wasn't up for the draft. (Lesnar, Mark Henry, and Rico are presumably being bumped up to the big leagues, but they're exceptions.)
b) Dunno. I think that'd be a pretty amusing angle, but then I'm a Test mark. Of course, just because Test shows up at Raw doesn't mean Flair has to book him, or even let him in the building, but he could always do a run-in. Maybe Vince will send him over to get the Hardcore title back from Raven.
Not at all HBK was playing the dickhead who kept geting away and the Undertaker was playing the badass who was seaking revenge. RVD is a face in this situation and Kane is heel. HBK was heel Undertaker was face. The booking would be way off.