Various questions around using Tasks in the Collections Form

Hi all,

I have a number of questions around using tasks in the collection form.

We would like to make the Task Type un-changable, as well as the Planned Start Date.

Is this setup at task type level, a profile option or can this best be achieved by Forms Personalisation?

In the task type setup I assigned a Duration in days to particular task types, hoping that it would populate the Planned End Date. However this does not happen.

Where is the setup around this?

The Assignment Type and Assignee fields are greyed out. What is the difference between Owner and Assignee and how can I make the Assignee field editable?