a question, is it possible not to use LCD, just to leave that part of the PCB as it is (i mean the holes where the LCD need to be installed)?
Yes, leave it simply out.
If you leave the LCD out, is it still possible to program the midi set-up parameters?
You can create the setup with serges editor and send it to the MB64 with same result as with a display.
But display is a nice feature and i am testing my MB64 since 3 weeks and dont want misss one 