Can you steal Houses? like in morrowind or will your stuff disapear from chests? also is it safe to leave stuff lying around

You can kill the owner and then sleep in their bed, chests are not safe I think.

You can't sleep in an owned bed, and apparently (according to a loading screen) everything left in containers not in your home will disappear. So, not really. And I'd also assume that cells refresh eventually, so leaving them lying around probably isn't a good idea, and I think NPC's might even take them now. Not sure though.