You should be fine with the 5" plate and weight. It's important that the pad be larger than the backing plate.
You probably won't need the cutting pad at all. Use the #83
DACP with the polishing pad. Often DACP leaves some hazing that needs to be taken out with a lighter polish, such as #80 Speed Glaze (also applied with a polishing pad).
In my experience, the 3M SMR doesn't work well with a PC.