Refer -
1.
GridView.RowCommand Event[
^].
Quote:
Occurs when a button is clicked in a GridView control.
2. Also check
How to: Respond to Button Events in a GridView Control[
^].
So, the answers to 1, 2, 3, 4 also implies to
RowCommand
event, if you are using the Buttons(ButtonField, Button, LinkButton, or ImageButton) inside them and you have a custom Command.