It may be possible to get most of this effect in-camera without special equipment, it shouldn't be to difficult to try - here's my attempt at deconstructing the images:

1. Shoot raw, we are playing with lighting and it will help if we are able to fix things in post.

2. The pictures are outside in the sunlight, try mid morning or late afternoon, it's not golden hour but we generally don't want to shoot in the harsh mid day sun.

3. As always in daylight, open shade and a reflector can be your best friends, direct sunlight isn't that flattering,

4. The subjects are completely in focus but nothing else is - so use a depth of field calculator and set the aperture as wide as possible while holding all the subjects in the area of acceptable focus.

5. The bride's dresses are always very well exposed (very white but not blown out), so meter on the dress so the camera meter is saying +2 (+/- one third, depending on your camera) you can take a test shot of only the dress and check the histogram (it should almost touch the right without actually touching) - set the shutter speed so the dress is +2 - don't trust the picture on the LCD only the histogram.

6. Make sure to compose the picture so there's something except sky directly behind your subject but still leave a lot of sky in the picture, the sky will blow out - let it.

7. Test different directions of the sun, don't include the sun in the picture but if the sun is to the side and slightly to front of the camera you can get "hazing flare" that will reduce contrast and make the image whiter and softer, if the sun is behind you the image will be more contrasty and sharper.

8. Set the white balance on the dress (you can do this in post) to make sure the dress is really white - but adjust a little if you need to get good skin tones

I don't have time to try it right now but I hope it works