Just one SPDT toggle switch (no center position, so ON-ON, right?): now I am curious
Yes that is correct.
This is what I propose:
The toggle switches are arranged in an N by N matrix and the Arduino continually scans the switch positions and keeps a look up table in memory. If the Arduino detects a change in switch position it pulses the appropriate coil.
Every so often the Arduino could step through the look up table an simply pulse each coil called to do an absolute configuration to give some belt and braces.
The Arduino would be able to set any time pulse to any degree of accuracy (within reason).
As stated the coils are pulsed via standard & cheap, driver chips which have 8 channels. The Arduino selects which channel to pulse.
I like chemelec's pulse circuit, but you either have the option of providing a pulse circuit for each coil or using some time dependent function which is fairly complex and possibly prone to glitches.
It also compromises the user interface, and has less flexibility, in my opinion.
It would then be fairly straight forward to hook up a small graphics display (cost around £6UK) to the Arduino and then the sky would be the limit.
You mention point tell backs: that would also be simple with an Arduino at the heart of the system.
I would be inclined to go for an Arduino Megga (£8UK) though, rather than a Zero.
The software would be simple to write and good fun.