There are over 30 tasks available out of the box and Federation Services is adding more all the time. This is the most popular extension point in Federation Services.
You can choose and configure job tasks on a per-job basis from the Tasks tab in any given Job.
You can re-order the pipeline by dragging and dropping the tasks. You can delete tasks or add new tasks.
The default recommended thread count is 1.
These tasks run in order, meaning if something is changed with the documents or metadata in one task, then the following tasks will see those changes.