8 with Midibox NG.
MB-LRE8x2CS has notthing pre-assembled. If you want the LEDs already soldered, go for MB-LR4x2CS / MB-E4x2CS.
Typically you can configure this to switch between the different modes (speed) of the encoder but you can assign any parameter to the command.
Minimum: 1 core (any model: PIC, LPC17 or STM32F4 based core). In case you want to use the built-in switch of the encoders, you need to add a DINx2 module for each MB-LRE8x2CS. You can find the different Cores and the DIN modules in the SmashTV's shop.
The faders and a AIN module (also in in the SmashTV's shop).
You should consult the midibox page about the AIN module and use the search function of the forum to see if someone as already tried this type of use.