Hello. I've returned to a field that requires some hazardous location design. I struggle trying to use the NEC book to understand anything at times. Basically- we have a skid that is determined to be in a CLI,DV2 environment. A remote I/O panel will be located on the skid. The intent was to have a Nema 4X box with all internal components listed for CLI,DV2 (Basically PLC I/O modules). On the skid there will be a mix of pressure/temp xmtrs and solenoid valves (most likely CLI,DV1 rated).

My questions would be:
Is the Nema 4x panel with all CLI,DV2 components acceptable to be on the skid? Can i have a supply fuse?
What rating do the devices need to be on skid? I understand CLI,DV1 would be acceptable but not needed for DV2. Would I try to use Non Incendive devices or design? If so- how do I find out exactly what is required? Are barriers required for NI or just IS? Typically we use RTD's with a transmitter in the head (PR 5333D).
Where can I go for training to learn the correct methods of hazardous location design?

Any help would be appreciated. Thanks.