It's a good practice to provide alternative interactions. And while pinning and unpinning an item is possible per mouse, some users might prefer or need to use the keyboard. In this case it's expected to have a command "[x] Pin document" (could also be done without the checkbox using different labels). If this command is added we should also provide an option to "Remove this document".
Agreed. See also bug 126404, originally suggesting a right-click solution, same as its duplicate bug 155965. It's already available for the Templates view, so users might expect consistency there. Eventually, the view will become too busy with overlay icons. (In 7.6, we already have 3: document type, remove document from list, pin to top.)
*** Bug 155727 has been marked as a duplicate of this bug. ***