As I understand it you have a choice to not fight Vader, but I don't know for sure and how it's supposed to work out.

I highly recommend that first part, it's totally cool as the fighting style does reflect Vader's character as seen in the movies.

*completely forgot that Force Lightning bit. I think I only played the saber styles, and totally loved beating the snot out of Mace Windu, although Dooku was hard*