This is a great video on how to resurface a concrete counter top. If you don't have access to an extractor machine you can rinse the counters with water and scrub brush and then shop vac up the water after the rinse. You can purchase a 7" diamond pad for your angle grinder at your local concrete store. You can order the Creto Top Seal and out more about concrete resurfacing at https://cretoseal.com/