Hay baler electric tie automation

I'm new to Arduino and I've got a little project I would like to pursue but would like ask a few questions before I get started. We've got a New Holland BR 730 round hay baler. When the bale chamber gets full it hits a contact that triggers a 12v light/buzzer on the control box that's mounted on the tractor. After the full bale warnings, there's a toggle switch that activates a 12v actuator that extends the twine out towards the bale. After it has been fully extended the toggle switch then reverses the polarity to bring the arm home.

What I would like to do is set the control box up so that when the buzzer goes off, you can press a button that would activate the extension of the wrapper arm for roughly 10-15 seconds. Once it is fully extednded, pause for a second, then reverse back 10-15 seconds to where it started from (which cuts the twine).

I was wondering if anyone could help me get started as far as what i would need.

Any help is aprreciated!

replace the toggle switch with a relay (12volt) relay to have contacts with a similar rating as the toggle switch.
Arduino can be triggered by the buzzer (Digital pin goes high) delays 10-15 secs trigger the relay .......
Example relay http://www.ebay.co.uk/itm/5V-Relay-Module-for-Arduino-AVR-PIC-5V-1-Channel-Relay-Module-/141228416894?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item20e1de9f7e
cheers
peter