Display zip files as 'gallery/thumbnails' & open

Complete newbie here, sorry for what is most likely a basic question.

 

I'm trying to create a comic book reader and need some tips.

 

I want to be able to set the directories (multiple folders), that then show in the app as thumbnails, sorted by their folder structure. The files are technically *.zip or *.rar files, but they're renamed to be *.cbz or *cbr, which then contain an *.xml file with meta data, and the pages of the comics as *.jpg.

 

How do I:

- Set directory locations so as they are remembered by the app

- Display the files (thumbnail set as the first image in the file)

-  Open the files to show the images

 

Sorry for several questions, but it felt like that was needed to pull together a complete answer.