The video on the home page shows the first step as marking the shoreline. Can that step be skipped and a chart made with no shoreline?
Thanks

Yes - shorelines are entirely optional.

If the shoreline is skipped does the mbtiles export include all the area outside the tracks, i.e. as a blank tile

If the shoreline is included I assume mbtiles only includes the area within the shoreline?

An MBTiles export will include the full geographical extent of the finished map project - whatever is visible in the map view of the project once it has been generated (you can see the "extent" of the project by double clicking within the window or using the "fit window" button in the view menu). Any empty areas, that would result in an entirely empty/transparent tile, are not included.