No, Vegas cannot access the Xplode card's features. As nice as the Xplode is, a fair amount of what it brings to the table is already in Vegas, minus the realtime output. It would indeed be wonderful to have some of this sort of hardware support in Vegas, but I doubt you'll ever see it. The Xplode is based on fairly old technology and hardware is becoming less and less an issue for DV and DV output.
For the transitions and compositing layouts, Xplode isn't any different than using Pixelan in Vegas.