A Raspberry Pi can not produce the baud rate required by the MIDI standard without a great deal of bother so I would forget that.
Yes you need a proper driver for the motorised faders, no processor pin is going to be able to power that sort of motor directly. You need a H-bridge driver to move the fader in both directions and requires two output pins. Also you need another two for monitoring the end stop switches and finally an analogue input for reading the value. So that is six pins per fader. Look into port expanders, you will need them on this project.
Now I had to look for arduino simulator before doing this in real life ...
The problem with an Arduino simulator is that it is not very good at simulating outside components. My advice would be do it for real.