On your first point, the headphones look high quality enough to justify the purchase of a soundcard. My standard recommendation is the ASUS Xonar D1/DX [PCI/PCI-E] which goes for about $75. If you need to go cheaper, the next best option is the ASUS Xonar DS/DSX [PCI/PCI-E].
On the second, spec wise, I'd imagine the onboard chipset offers higher quality on your laptop. I know desktop chipsets offer better specs then the Dreambass lists...Don't think its worth a purchase.