I've never done BFL, but I'd give the program a try as written. If your diet is cleaned up, you can see results with minimal cardio. From what I've read, too much cardio can do away with any muscle gains that you're trying to make. I'd start with the program recommendations then add more if you stall to shake up your plateau.
Alot of serious weightlifters do something called HIIT (High Intensity Interval Training) where you go as fast as you can on cardio equipment of choice (or outdoors) for 20 seconds, then recover for 40 seconds. Or 30 secs:60 seconds. For a total of only 20 mins including warm up and cool down. I've just started giving this a try, but most of them only do that twice a week.