You'll probably find yourself going lighter on subsequent sets because you will be more fatigued, but I don't believe you need to up the reps to lose weight. It's all about intensity, and getting your metabolism going. Low intensity cardio is great for burning fat while you are doing it, but as soon as you are done, your metabolism drops. High intensity stuff raises your metabolism while you are doing it, and then even more afterwards (for a day or two, I've seen studies but forget the actual number of hours).
Definitely get the carbs under control if you are wanting to lose fat. It helps me to eat my protein first, then some fiber and maybe a salad (no dressing or light italian), and then I'm not terribly hungry for carbs.
As for the ALA, I take amounts depending on my carb intake. If I'm going to eat light carbs (just veggies), I'll take 250mg. If I'm eating a higher carb meal, I'll take up to 750mg. I'd be interested in hearing what amounts others are taking.