Re: Carbs around workout only
I wouldn't worry about it mate. Do what makes you feel the best and perform the best, you could do a carb backloading approach which may help you recover better after workouts (if you train in the late afternoon) and you will be a bit more insulin sensitive if you don't spike insulin throughout the day.
Don't forget though that protein is insulinagenic also, so you will spike insulin from a whey protein shake for example.
Maltodextrin probably isn't the greatest thins in the world to have intra workout due to the slow gastric emptying and the fact that it site in the gut and may give you issues during your workout. Probably best switching to a carb which has faster gastric emptying but will supply you with good energy throughout the workout, something like cyclic dextrin if budget allows.