Finding add-on

in the past i had fire fox programs, one showed bookmarks in a window that slid out from the left side when i ran my courser over there then disapeared when i moved the courser away. The other on a picture I could put my courser on the picture, left click on it, then one of the choices would tell me the exposure information of the picture.
I tried searching for these, obviously it was beyond me as i am only able to get a few choices.
thank you for your help.

Firefox has a built-in bookmarks sidebar. There used to be an extension to slide it out only when you hover over it. That is tricky to replicate using custom style rules (in a userChrome.css file), but currently, I think that is the only method to show or hide the bulit-in sidebar.

Example style rule for the Tree Style Tab sidebar, which perhaps could be adapted for the bookmarks sidebar, on a site where lots of style hackers contribute:
https://www.reddit.com/r/FirefoxCSS/comments/7emhsq/my_compact_treestyletab_css_and_sidebar_hover/

Newer bookmark-related extensions generally work with a drop-down list from a toolbar button. In theory they could inject a sliding panel into the page, but for privacy reasons, I think you probably wouldn’t want the website to have your bookmarks list.

The information you mentioned about images – originally embedded by the camera – is often called EXIF. If you search for EXIF maybe you can find something useful.