All the devices have breakout tampers that should be used.
Mechanical protection should be as per wiring regulations.
BTW I hate when the bottom knockouts are used on Premier cabs, causes hassle if you need to put larger batteries in there. The mains connection has it's own hole adjacent the mains connection.
Grading would only be relevant for a company installing a system for you. This is based on a RA that the company would do. DIY effectively voids any grading, you can fit to Grade 2 standards but means very little.