Hi,
Sounds like a great project. Please do keep us up to date here. When it is ready, Github would be good.
is it necessary to implement 3 "home" switches (magnetic) to ensure that every update stepper will go "home" and after that will go to new position?
It is necessary if you want it to be very reliable, with power on-off etc. You could start without it and manually set start positions. It may be easier to use small opto-interrupter modules to find the start/home position compared to magnetic/Hall effect??
It might be good to send each indicator home and then to position when it is updated. I think you might hear the stepper move and know there was an update. Or use a small buzzer for that?