1) During the winter, it is free heat. I don't think this is something new to anybody, that if you open your curtains the sunlight will warm the house, but I don't think we get into the habit of it. Make it a point in the morning routine to walk around the house and open your curtains, shut them at night. The amount of time you spend doing this will be more than compensated for the less time your furnace has to kick on.
During the summer, the opposite is true, close those puppies during the heat of the day.
2) Why are we using electricity to light lightbulbs during the day? I am guilty of turning on lights during the day instead of walking over and pulling up the blinds. How lazy am I? I think you just have to make yourself get into the habit.
Make yourself get into the habit of daily opening and closing curtains.