Which input is left and which is right?

Both signals are processed independently so it doesn't actually matter which way round you patch them as long as the outputs are connected the same way round. The input with a little white dot next to it is the mono input and it is automatically duplicated to the other channel if only one cable is patched. Many other stereo pedals are labelled L/Mono and R, so feel free to use the input with the white dot as the left input for consistency if you prefer.