How much is too much? Two questions

Question 1: I have 3 night stands, a high top dresser, mirror/dresser and a mirror on a stand all in brownish color stain. I really love the silver/mirror metallic look, so I was thinking about doing one of the night stands this way (which will be next to my white chair with a black and white throw and lavender pillow in between two windows with black and white drapes). So for the other pieces I was thinking white cabinet with silver/gray drawers and black hardware.

Question 2: I purchased gray, silver, white, black, lavender and mirror accent pieces in the way of frames, euro shams, lamps, mirrors, flowers, candles, etc. So what is the repeat for choosing colors or patterns? Do I need to introduce any other colors?
Thanks!