The part about working up through grits with a wet sponge is the real trick nobody talks about. My buddy Tom did a bar top in his garage and skipped the wet sanding, just dry sanded it, and the dust clogged the paper so fast he went through like 20 sheets and still had scratches. He redid it wet and said it took half the time and came out way smoother. On the sealer thing, Tom used a solvent based one the first time and it went amber after two summers out there in the sun. His second top he left bare and just rubs it with a food safe wax every few months, says it looks better now than the sealed one did. For a grill station I'd probably go bare or use a clear water based one made for outdoors, the sun is what kills most of them.