10.2A sounds like inrush current draw. 672W is right on 5.6 amps, so I would expect normal current draw to be around that much. I would expect that a peak would be 10.2A at power on for inrush current.
Not sure why you thought laser projectors were more power efficient. They are not. Lasers are not an 'economical' lighting source. But, the light output is much more consistent, and the solid-state light engine is much more durable over time.
You can always contact NEC directly and ask them for clarification. I call manufacturers all the time with specific questions about their products. Including NEC.
Not sure how you are going to create '1 projection image', as this isn't always as easy as it sounds. Projectors must be color calibrated to very exact measurements to ensure a proper edge blend, or butting, or overlay. That process typically must be repeated monthly or so for best results over the long term.