"Why can't I wear the makeup I wear everyday, on my wedding day?"
Because you don't get married everyday. It's your very special day (if not the most special day) in your life! One of the reason why your makeup choices change is because of the photographs. Of course you want to look gorgeous in person but you're not taking all those pictures to look washed out or tired in them. You want to look like you just enhanced... fresh, beautiful and happy... in person and in the pictures.
"Does wearing a white dress make a difference?"
Yes. White or any variation on it. Some artists believe that white is the absence of all color. So you need to wear a little more color on your face, especially the lips and cheeks. In general, rosy beiges and soft pink tones are good choices for women with light to medium skintones and plums, rich peaches and rusts are good for women with darker complexions.
"If my photographer is taking color and black and white photos, does it matter?"
Yes it does. You may like the way that rich, deep lipcolor and eyeliner looks in person, even in your color photos, but in your black and white photos you could end up looking like Elvira!
"Do I need to consider my color scheme when choosing my makeup?"
Yes, you should consider it but don't let it dictate your makeup choices. For example, if your bridal party is wearing red, you don't want to be wearing fuschia nailpolish and coral lipstick. The colors will clash in your pictures and it will appear that you weren't all on the "same page". I find it best to keep your nails neutral (soft, light colors or a french manicure are great!) And your makeup soft and suited to your skintone.
"What do I need for touch ups during my wedding day?"
A pressed powder, to reduce any shine. Your lipcolor, lipliner and gloss are a must. Whatever else you may need is up to you.