Where would the data come from ? 
Ubooquity relies entirely on what it find inside the comics/books files. Do you have some files containing the informations you mentionned ? (index, summary, authors...)

That could be done. Although I suppose that a consistent enough naming
scheme should be sufficient to organize your content by date.

I've been asked for this feature several times.
Ubooquity is a "content server": its purpose is to allow file access, not to modify them. So a metadata grabber would have to be done in another project (Ubooquity never modifies your files, and storing metadata outside of the files they describe is a bad idea).

I have almost started working on a metadata grabbing software. But after having dug a little into the amount of work required to have something efficient and easy to use, I have realized it was not a realistic task.

At some point in the future, Ubooquity will read and make use of the metadata contained in the "comicinfo.xml" file some comic files contain. But this file will have to be generated by another software.

I'm not sure I understand what you mean by "sub index".
Do you mean a specific way of organizing comics, like by series ?

One thing I have planned for the future is to read and use the "ComicsInfo.xml" metadata file contained in somes comics. It has informations on the current series, the number, the date, the authors etc. So I'll probably add sorting options related to these additional metadata at the same time.

The license text has alwasy been included in the Ubooquity distribution. But it was only visible in the "About" section of the options of the graphical interface.
Since many (if not most) people use the command-line mode and never see the graphical interface, I have recently added the license to the website. The next version of the webadmin (the web interface you use in commmand-line mode) will also have a link to the license page of Ubooquity web site.

I see how this could be a problem. I'll add an option to disable autoscan.