I rarely bother with these, but I've certainly used them occasionally. I'm still moderately amused by the non-updated roadside rest areas that still have them, as I consider folks stopping for an hour or more beside a busy highway to fire one of these up and cook their lunch.
Apart from using height to control temperature, you can also normally build your fire on only one side, since the grill surface is very large unless you have a very large gathering to cook for, so you can move things off to the side for finer control. Likewise, you can pile the coals up higher or spread them out with some tool that you bring. It's essentially a slightly more convenient campfire, as opposed to the sort of grill with dampers to control airflow.
It's not normal to put already-hot charcoal in one, but if you want to, a metal shovel would be appropriate. In most locations you should drown the fire completely with water at the end of using it, though local practices may vary somewhat. Some (evidently not this one) do allow the grate to rotate up at the highest level so you could use a chimney-type starter, but capturing the grate in some manner is normal, since some people will steal them otherwise.
As in any other kind of grill, actual charcoal is faster and easier to light than briquettes (which are mostly coal dust, rather than charcoal at all - and slow and annoying to light. And foul-smelling if they are "easy lighting" ones, so it still takes a long time before the stink burns off and you'd want to cook food over them.)