How do you call a function in the controller/click a button when the user presses the enter key? I have a form with a submit button, all inside the same component. Thanks!

I created an outbound change set in sandbox.

My question is, if the contents of  the change set (ie. a Visualforce page code) changes, does this mean I need to create a new change set?
or does the original change set know that the VF page was updated?

Thank you