problems with slug and view in custom post types

[thomask]

when creating custom post type, there are 2 minor problems

1. when setting rewrite to false, it is not possible to edit slug (edit button missing) - this is wrong as slug is needed e.g. for get_post queries by name
2. if the post is set not publicly_queryable, then anyway the post edit screen shows "View [custom post name]" and "Preview" button, which then points to 404 screen.

Related: #20098