Re: Gas hob question
Year im not sure of as they change monthly.. but current would be a isolation valve to isolate the hob on its own which is accessible without any tools having to be used.
Anything above the burners must be 760mm unless manufacturer states otherwise and that would mean that the hob manufacturer and extractor would need to have the same measurements. if there is only the instructions for the hood then its 760mm same if only installation instructions for hob and none for hood. so realistically it should be 760mm as nobody ever has both to match.
Room should have outside door or openable window and if no outside door then normally a NON closable vent is required.
Bryan