Yes you can but within the lore and laws of the game world. As to your actions changing things within the game world, well they do. You go to a small populated system on your own, you can have great fun changing things around in that system. Of course you can change stuff. Whenever you do a mission, hand in bounties, hand in combat bonds you make a change. It may not be visible, but you still make a change. I would like to see some of the changes more visible though to be honest. The BGS is pretty good, but is lacking with it's visual representations of its different states.