Is non-alcoholic beer nothing else than unfermented wort? That is to grains which the sugars have been cooked out of, bittering agent added and then just the step of fermentation omitted or is there more to it than that?
No, it is fermented to break down the sugar; otherwise it would be very sweet and sugar cannot be cooked off. After fermentaton is complete, the alcohol is removed. Note that most NA beers do actually contain a small amount of alcohol: < 1%.