The Document Activity Timeline and the Site Activity Feed serve different purposes.

This might require a different UX....

We need to merge Updates (Version history), Citations, Discussions, and Collaborators activity into one ACTIVITY TIMELINE!!!

The Document Activity Feed is ordered by time. Is it possible to order it by other criteria?

In the Feed, comment feed items always show the exact versions.

Steps:

Comment Feed Items show exact versions as a blockchain or time machine. (NTH: show a message on the block feed item that there is a new version of the block).
Clicking a feed item will open the exact version.
The user will have the option to go to the latest option.