Diamond grinding works fine for the RockSolid metallic. You don't want to seal the concrete before applying a coating or it will not adhere. The coating is a sealer. It can be applied to the wall base as well.
For the best results we would suggest applying a single coat of their standard grey polycuramine to act as a primer. RockSolid tends to penetrate well into concrete and some people have had issues with color uniformity problems due to the coating being thin in places where it penetrated well into the concrete - especially with concrete that was prepped via grinding. The grey coat would be the sacrificial "ugly coat". It will also provide a much more consistent coverage rate of the metallic epoxy and produce a deeper look.
You may want to
read this article about a RockSolid metallic installation to make sure that this is what you want . The women that installed this particular floor do a great job with their videos of documenting the installation as well as giving a one year review of the floor.