I am still only looking for a solution to the external pressure sensors and the flow meter, not for the pump. All pump information will be done separately. My question is more about how to [u]power and connect the pressure sensors and flow meter.[/u]
As you say ALL have M12 connectors, use the associated cable to connect to your controller and power supply.
All sensors can be supplied from the same supply.
In practice the cables connect to a terminal strip, then the strip connections go to the controller or power supply respectively.
Use a commercially available 24Vdc SMPS to power it, why commercially, because you will be guaranteed low noise, stability and reliability.
If the cable is not long and near mains power, use the 0 to 10V outputs of the pressure sensors via a potential divider to the controller, for stability I would suggest to use the controllers internal reference or an external stable reference voltage.
The 4 to 20mA loop signal can be read with a shunt resistor converting the current into a voltage for the controller, OR you can invest in a converter module that converts loop current input to voltage output.
Can you please tell us your electronics, programming, arduino, hardware experience?