Cell-Tech isn't the best choice. Muscle-Tech products in general suck.
http://www.bulknutrition.com/produc...products_id=871
Here's how unpopular cell-tech is with fellow weightlifters.
Total Calories 300
Calories From Fat 0
Total Fat 0 g 0%
Saturated Fat 0 g 0%
Cholesterol 0 mg 0%
Sodium 60 mg 3%
Potassium 150 mg 4%
Total Carbohydrates 75 g 25%
Dietary Fiber 0 g 0%
Sugars 75 g
Cell-Tech weight gain is directly related to the ungodly amount of sugar per serving. If you want to loose weight, you don't want 75 grams of sugar, pure and simple. Regular creatine mono will be just as effective and better for your goals.
As for how and when to take creatine, check out some of the past posts. It's all pretty much covered.