Thanks for the feedback Dave, that helps us help you.
Okay, from what you say with the green grounding screw making contact with the disconnects metallic case/frame ALL IS LEGAL based on my very rusty and outdated NEC knowledge so NO WARRANTY. However, again with proper Copper and Aluminum compatible junctions, I still prefer (even if NOT NEC required) the bare No 4 Copper Equipment GroundING Conductor bonded to the Neutral Grounded Conductor (at a single point) WITHOUT IT HAVING TO USE THE METAL CASE AND WIMPY GREEN GROuNDING SCREW AS CONDUCTORS. I just view the small grounding screw MORE as a method to bond the metallic case to the newly established Equipment GroundING Buss/Connection versus it and the case/frame being relied on for conduction and the electrical connection for bonding Neutral to Mother earth Ground THATS MY STORY N IMA STICKIN TO IT.
HOWEVER I would not use BOTH, if you run the bare copper to the Neutral (instead of the small case lug, with a proper junction method for copper/aluminum) Id then consider the green grounding screw as the method to bond the metal case/frame to the Equipment Ground. BUT THATS JUST ME DONT GET UPSET. The main thing you are doing (when you earth ground the Neutral) is to tie Neutral to mother earth for lighting and surge suppression and I like it direct NOT via green screws and metal cases. I don't have a problem with the green screw being used to bond the metal case/frame, that's how I've seen it.
GROUND RODS as I said before if your utility and local authority consider the single driven rod as sufficient I wouldn't worry with more (although sure drive all you want). In my day we drove one rod them tested it and if it failed we drove another rod and re tested, but if it still failed we didn't drive more rods. As I recall the NEC says tie to all readily available grounding electrodes which includes buried metal pipes and structural steel and "made electrodes" sucH as driven rod or rods. If there were no other electrodes then we used "made electrodes" such as driven rods.
I WISH AND HOPE SOME OTHER MORE CURRENT PROFESSIONAL electricians and engineers would comment on my method and tell how they preferred it, is this just me lol Anything wrong with my preferences??
John T retired, rusty and always willing to learn