As stated above, you can put the LEDs in any pattern you want. There is only one Data-In from the processor. That will be led(0) in your program. Each WS2812 daisy-chains the data to the next WS2812. If you cut a strip, then the data-out needs to be wired to the data-in of the next strip.
The data is in series.
The power (+V AND ground) is in parallel as much as practical.
