Yes, one fan connector on the motherboard is enough.

Unfortunately, I couldn't find this information anywhere at the manufacturer's or on the web in general. With a bit of luck, someone else will answer your question.

Yes, that works. If it absolutely has to be a glowing fan, this is certainly one of the best.

Correct. The delivery includes a controller with which you can switch between 5 different modes: red, blue, white, green and 256 multicolour. For more detailed explanations please have a look at the manufacturer's link :)

Yes, 3 fans, the mounting screws and the control box which has 3 functions with solid colours and a spectrum mode and then a possibility to block one colour of the spectrum, so no software directly provided. However, please note that these are the 256 colour versions and not the new 16.8 Mio colour fans, although the latter are not yet available in our country

Yes, you can see the ring from both sides and you can also screw them on upside down.

Unfortunately, the manufacturer does not provide any information on this. However, we assume that the second slot is intended for expansion.

This is not a set, but only a fan with colour control that can display 256 colours. Alternatively, the fan is available in other (colour) variants, but these only display one colour.