The rug size looks good. The mirror may be a bit large. It should be 2/3 to 3/4 the length of the table. The frame is thin though so it might work.

I like it, goes with the style of ur room. if it looks to wide then maybe flip it to rectangular, see how that works out.

I think both sizes look just right. For the rug, avoid any more geometrical shapes and look for something with a softer, more muted pattern. Choose a color that coordinates with your adjacent rooms.