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%.
It is fermented like in the previous question but nowadays there is a genetically modified fungus that can break down the sugars without creating alcohol. When normal yeast is used (it gives a better taste) Commercially the alcohol is removed under a vacuum to lower the boiling point of the alcohol even further. (higher temperatures affect the taste of the beer) The removed alcohol of medicinal grade and is sold on to pharmaceutic companies.