Restoring both handles to an anchor point.

Hi folks,

So I create an object with a closed path. I use the Convert Anchor Point tool to bend and reshape a line in that object.

Two questions:

How can I begin the reshaping by using only one handle instead of being forced to use both and then going back and deleting the second handle.

How can I restore both handles when I come back to edit and find only one is there to play with?