Presume there is the 12V PSU between the mains and the MPD? The lightning bolt scared me
Don't know if earth is absolutely necessary to the plastic back box since the DRB itself does not have an earth connection.
This daisy chained configuration looks ok. You can of course also use other spurs on the MPD to do a star or part star configuration if you wanted.
As you are just starting, may I remind you to commission (plug in) the DRB and LPS modules one at a time. The PCU is supplied pre-commissioned these days.
Of course there are umpteen other things you could do, but one off the top of my head - how about also button 1 on the DRB acting as a light toggle and the LED next to it acting as a light state indicator? That should exercise you Cortex programming skills. Also for fun you can try remote access via the Cortex web server, or get the button press (or indeed the light state change) to send you an e-mail.
Also, it would be possible to implement your stated functions in Reflex alone, i.e so that they can run without the PC. Again perhaps another good learning exercise.