Pins uses

[AlekseyFedorovich]

There are several pins I can't understand the use cases and I'm not sufficiently experienced to deduce it from the schematics: how could I found what's the use of the following pin:

• VP
• VN
• CMD
• SD0, 1, 2, 3
  I could not find anything similar to a manual.

[theloukou]

CMD and SD0-3 are SPI pins, connected to the onboard flash chip (where your code lives). Don't use them if you don't REALLY know why and how to do it.
VP and VN feed a low noise amp (a differential amp). If you don't know what this is helpfull with, then leave it alone :P
You can use them as normal ADC inputs though, or as digital inputs only).