Thanks for the feedback,
RE 1. : The one I use the most is hierarchical and it is there. However, it would only seem natural to have the full list available.
RE 2. : I reaffirm my original comment. When importing for the first time, the hierarchical layout obtained is different from the one produced by applying the hierarchical layout after import. You are correct in stating that afterwards, the hierarchical settings are retained.
3. : It would be convenient to the user to set other layout settings such as label placement. Such settings that can be automated would make a better user experience.