I know wood ash is fine in compost (coal ash: NO) I don't know really what lump wood charcoal is, sorry
Yes and no greg4, I'd burn it first, without the use of any lighter fluid, then the ash can be spread on your beds.
you can grind it up small and mix it in with the soil, it'll break the soil up if its clay in the same way as organic matter, but it wont break down and charcoal doesn't rot.
The fashionable name for this is biochar - Wikipedia has an article on it. Benefits include enhanced moisture retention.