Yea no star destroyers shields are for blocking debris and small to medium asteroids and lasers (any asteroid due to cosmic speeds+ mass is roughly 500x more powerful than a NUKE of the same yield) yea hyperspace and slipspace are different but BOTH are FTL and star destroyers are faster. As for ground war ild love to see afew ODST teams get PWN3D by a legion of troopers and 4x AT AT (the battleforce aboard 1x star destroyer) and star destroyers ARE DESIGNED to sterilize the surface of a planet till its devoid of all life (just 1x btw)