You should try to get up from your desk for a few minutes every couple hours and walk around, do some stretches, etc. You can do leg lifts in your chair, various arm exercises, etc. Try a google search for "chair exercises".
Here's one I found that has really good work place exercises:
Here's another one:
Of course, there are certain exercises that you won't want to do when wearing a dress and if wearing high heels, you'll probably want to take them off; also most of those done in a chair, were chairs with wheels, so you'll have to make sure to lock the wheels of your chair if possible, or brace it against a wall, etc so the chair doesn't slip from under you and cause an injury.
Hey. Well eat healthy foods that your body processes easily. Like fruit, whole grains, vegs ect. But fruit should be 3 or less servings a day. I find popcorn with salt on it a really good snack as it has only about 100 calories for 3 cups.Or veg sticks and humps eg carrot sticks, cumcuber,calerely (0 calories) Or heathies has yum chips, rice wheels that are from 60-80 calories and heathly.For food wraps are good 130 caloriesplus ffillings.you can grill wraps with topping and make heathly pizza :)