A:Answer Yes you can up-grade the Msata drive, its extremely easy, but there is no room to add a 2nd hard drive, there is however a HDD1 slot on the motherboard which would need a Dell proprietary cable (5510 XDYGX) but like I say there is no room to install another HDD, if there was such a thing as 5510 XDYGX to msata you just might get another drive inside.
This is a great computer, I returned an Asus Q304 which was cheaper to get this Dell, the Asus is a dog.