So I am assuming when you say you would have went with the BAT strut/spring kit you meant the "European Handling Kit" @ $640?
If a guy went with this would any additional parts need to be purchased? Or is this kit all I would need to lower the car about an inch?
yes the BAT kit has been around along time and has been used by many. It will lower the vehicle about an inch. As suggest it would also be best to replace the strut mounts at the same time. Optional things would be the end links, swaybar bushings, control arms, etc.