You can find the list of outdated apps on the Applications section at the back end. There will be an "Update" button if it is outdated.
This one?
There is no update-button on any of them.
These items that appear on the story form can only be from apps. Plugins can never generate these buttons, so I am not too sure what you mean by "some of them are apps and some of them are plugins".
I simply mean that I don´t understand the app-section.
There are 4 pages with apps, they belong to a "group" and have an "element", but I only see a name and I have no idea, what is which app for.
The mixture between apps and plugins is from the dashboard. I remember that some of the boxes on the dashboard campe from apps, others from plugins or modules. I don´t really know if those four pages are only apps or also plugins or modules.