Thank you for the feedback. We certainly need to allocate more time to document the apps. We should be able to update a number of the description around mid-March.

As for removing apps - you can remove apps completely. You need to enter "manage" mode in Studio (magic wand) and this will show "Delete" icon next to inactive apps in Studio launcher. Note, that you need to deactivate the app first.

As for adding "Add" button, we actually routinely do this for various projects, but it's not something we want to do out of the box. You can add a button wherever you want using a menu block and placing it with the action you want on any page.