Sol, dextrose is best used with your protein shake, 50-75g's is a generally used and good amount. Brand really isnt that important, just get a big bag somewhere online, and take that 50-75g with your postworkout protein shake, they are generally tasteless and mix very well.
Taking the 2 scoops of whey before bed is better than nothing, but you read a lot about the slow release protein (casseine) because it absorbs in your body over a much slower period, usually from 7-8 hours, whereas whey is MUCH faster absorbing. You can buy it in powder form just like whey, or most people like myself like just getting it from food, again most people choice is cottage cheese. Try depending on your goals, 1 cup of cottage cheese, with 1oz chopped almonds, and splenda to taste before bed, I've made it a habit and have come to like it. GL.