Grouting Caulking Sealing Advice Needed

Finishing a remodel and need to ask a couple of questions. The tile guy did not grout or caulk around the floor grates in the showers. There is a 1/4" gap around the ring that the grate screws down into and the ring can be lifted off off of the drain flange! Is this meant to be grouted around or caulked around? Also, he did not grout or caulk around some glass block walls he did for me. Again there is about a 1/4" gap from the grouting to the edge metal. Does this get grout or caulk? Is there a special type of product? And finally I have some slate floors, walls and some onyx floors and walls that were done on cement showers and bath and on drywall around countertops in kitchen and bathrooms. I want to seal them well to prevent water/ moisture from getting in. What is the best product for this?
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