At least 10 square meters are required.
Yes, and it needs customization.
Pay attention to surface cleaning, and do not accumulate too much dust or snow which will block the solar panels.
That depends on the light intensity. If the light is strong, there will be a weak current and voltage, but this is still very different from the bright light on a sunny day. The stronger the light, the better the power generation effect.
For solar panels, the series connection increases the voltage, and the parallel connection increases the capacity.