Is my schematics correct? (Atmega328p for solenoids control)
The area in Yellow needs to be fixed as PWM will not work.
Dont you want to put a cap on RESET to gnd for POR?
How far are all the cable interfaces?
What type of shielding do you need?
Do you have a functional spec for immunity?
Are you planning to do Susceptibility testing? Radiated Arc,  Impulse RF , Induction spikes etc.... if so what is your spec for dV/dt , dI/dt or field strengths for crosstalk from load to inputs etc.
if you dont make a spec, how will you know it wont fail? or when it will fail 


or if it is interface overkill./..\



It's like an architect who designs a bridge with elastomers and even tension supports and forgets about wind effects. If you dont define all the environmental risks, how can you say it passes?