Not much on this topic in the help file when you search for Batch.

1. Can this feature be disabled from worklist?

2. Can this feature be disabled for specific processes (due to corporate policy)?

3. What happens when the selected task items have different actions?

 Batch processing
allows a user to process multiple task items at once. Selecting the check box
permits the task item to be processed in batch. Clicking the Batch Action:
down arrow displays the actions available for batch processing such as
Approved or Declined. The task items must be selected to be included in the
batch. Checking the
check box in column heading will automatically select all task items for batch processing.