Answer for the missing Layout controls in the editor, after following up on Tom J Nowell’s great tip that it is a GeneratePress feature. Tom at GeneratePress helped my solve it with a filter. By default, the Layout box is only shown for those with ‘edit_theme_options’ capability. The filter changes it to the custom capability, ‘edit_ncpages’.
// Allow Layout metabox to be generated in editor.
// Otherwise only users with 'edit-theme-options' capability see it.
add_filter( 'generate_metabox_capability', function() {
return 'edit_ncpages';
} );
Or it could be just the ‘read’ capability, so anyone who gets into the editor has it.
Still haven’t solved the other part – nobody with just the custom role shows up in the author dropdowns, although they can author and edit the custom post type.