Ordnance Survey open data update

When and how can the Ordnance Survey open data layers be updated in the map editors?

Are there other places to view the layers, that we can then use to inform us when doing remote mapping? E.g. ZoomStack is a bit more recent and looks like OS StreetView, but is it? There is also an OS Maps viewer that is much more recent, but are any of the layers open data? Both those links seem to have a generic OS copyright statement in the corner.