As long as you are using only one PCM, you should keep the PCM at CAN ID 0. Otherwise you need to specify the PCM CAN ID in all Solenoid/Compressor constructors, as they default to 0. However, you can set the PDP to whatever legal (0-62) CAN ID you want with little to no consequences.
About SparkMaxes/Talons/Victors, there are two different ID pools : You can have a SparkMax and a Victor/Talon with the same CAN ID. You shouldn’t do this for all sorts if reasons, but it would work.
Either way, you should read this post.