Periodical management

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.

Sorry, a small mistake. I mean sub summary. For each item, list contents. Like from page 5 to 35, from 36 to 70 and so on... The contents, a small resume, history, authors... and other information.

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...)

probably indexing with names, like commonly used in video files.

for example: 
PC.Magzine.2014.july.pdf

time_magzine_2014_26.pdf
or time_magzine_2014_09_05.pdf

Science_v425_#6102.pdf

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