How should the smoke appear in the exhaust in a kettle charcoal grill

I don't usually pay attention to the color of the smoke. Just don't put anything on the grill/smoker until the charcoal has turned white or gray. This allows them to reach proper temperature as well as burn off and chemicals used to start the fire. If smoking, soak the wood chips or chunks first. They will burn slower and give off smoke longer, which is a good thing for consistent flavoring. A thick white smoke will be given off after first putting on the wood, then slow as the wood burns off. I prefer to keep the smoke less and cook at lower temps for longer periods, as the smoke gets deeper into the meat as opposed to thick on the outside.

You want thin blue smoke. While I don't have any good explanation on the chemical differences between 'blue' smoke and white smoke, there's certainly some advantage in taste. Blue smoke is a slightly cooler smolder from the wood, rather than an almost-burning-state.

Use chunks of smoke-wood (roughly fist-sized chunks, rather than the coin-sized chips of wood) for long-smoked BBQ. Put the smoke-wood on first, put the cover on and let the smoke-wood get down to a smolder before you put your meat on.

However - it is a fairly minor difference. I've made plenty of good BBQ with the wrong-kind of smoke when the food when on. If you're just starting-out, don't freak-out too much that your smoke isn't perfect. You'll have your hands full trying to keep it within your target cooking temperatures, which is more important!