Mandy:
Weather at Disney in March is lovely: it's not too hot nor cold. However, you will need to plan for its unpredictable afternoon showers and possibly chilly nights if a cold spell comes to town. Typically in March, my crew wears shorts during the day with a jacket tied around our waist to put on come nightfall. We have visited, though, when it was necessary to wear jeans and sweatshirts, so keep an eye on the forecast before packing. I always recommend buying ponchos for your family before you leave home so that they are all one color (and your crew is more recognizable in a rain storm in the park) and much cheaper than buying them at the parks.
The advice you received on watching the fireworks is half-true. Diners at
California Grill atop the
Contemporary Resort can see the Magic Kingdom fireworks or, if their dinner is early in the evening, return to the restaurant's viewing balcony later in the night to see the fireworks. So, yes, you can see the fireworks from the Contemporary but you must be a diner at California Grill. There are no windows at
Chef Mickey to allow you to see the fireworks. However, after dinner, you can hop on the monorail to its next stop at the Ticket and Transportation Center and get a wonderful view of the fireworks near the ramp to the Magic Kingdom ferry.
Wishing y'all a magical vacation!
Whitney