RE: Protein blend?
Whey is a fast-acting protein, whereas something like casein is relatively slow. People might have a blend of 1 scoop of whey and 1 scoop of casein around bedtime so that they've got something to "keep them going" through the night.
Personally, I wouldn't get too hung up on it. Sure, it does make a difference to a certain extent, but having whey as your only powdered source of protein is not going to hinder your progress in the slightest if the rest of your diet is in order. Don't go spending Â£00s on multiple types of protein powders/blends.