You can think of a task as a checklist that you can delegate with other teams. Let’s say you receive a ticket that requires an agent from another team to complete certain things before you can actually resolve the issue. You can add a task, assign it to the appropriate agent and even set a due date for it.
You can create tasks even if you want to split a complex ticket among your fellow agents for a faster resolution.
Yes, we can assign a task to a group while creating it or later by editing the task.

Tasks do not have an SLA that is calculated based on Business hours, however, you can set up a due date for the task
A task can be assigned to only one particular agent. If you need to create a task for multiple agents, we recommend creating multiple tasks and assigning to different members
We can automate the creation of Tasks based on specific conditions using the workflow automation. You can navigate to Admin-->Workflow Automator and create a new automator and setup the same
Yes, we do have email notifications which are sent to agents based on the task events. You can check these from Admin-->Email Notifications-->Tasks
Tasks can be assigned to a different group apart from the group to which the ticket is assigned to.
Yes, you would be able to view the tasks based on the agent by clicking on the tasks icon on the navigation header and view the tasks based on the group or agent assigned to the task.

While creating the task, you will be able to select the notify before option which will send you the reminder notifications for the task.

Yes, we can configure Ticket Closure rules which prevent the ticket to be resolved or closed unless all associated tasks have been marked as completed. You can navigate to Admin-->Ticket Closure Rules to configure the same. For more information on Ticket Closure Rules refer to the article here
Yes, you would be able to run reports on tasks from the analytics module. Navigate to Analytics and create a new report and choose the widget type to be as Task Widgets. This allows you to filter based on the task properties.
When creating the time entry in the ticket, you can choose which task is the time information to be added to. This information can later be reported on as well.

The Task is a standard module and is not part of the ticket SLA. We can set up a due date for tasks and have the agent notified before the due date of the task is breached.

We don’t have an option to modify the fields under Task section
We will not be able to re-order the tasks once they are added. While automating the task creation, the tasks are created in the order in which they are set up in the action block of the workflow automator.