I just released Tea Timer 1.7 which implements a few wishes from you:

• There’s now a rewind button for resetting an ongoing countdown to its initial value.
• The timer will be reset to the initial value, not the last pause value, after the alarm.
• The current widget’s settings will also be saved as default settings for new widgets.

Unfortunately it was not possible (neither with Python nor with Apple Script) to implement a backlink from Growl to Tea Timer to stop the alarm when you click on the Growl notification.

Anyway, Download Tea Timer 1.7 and enjoy!