Hi this is my second entry for the back hardware design
The back should be glass
For the size most people love a small phone so maybe like 5-5.5 inches would be a great place
For camera my suggestion would be to use the gcam software and integrate into the existing camera software by default
Usb 3.0
An alert slide would be great aswell
For colours I was thinking like black and the stripes to be gold or black and neon blue like tron