Regarding point 3: At 150 modules consuming about 25W each, your LED wall is consuming about 3750W max. An 80" TV will consume about 300W.
Power consumption of the LED wall will, however, be highly dependent on the displayed content. A white screen will consume most, a black screen basically nothing, but displaying only dark images is not exactly what LED walls are usually used for.
The equation is simple: The brighter, the more power you'll need, and an LED wall is, as you say, far brighter.