The replies you've received are correct as to the equipment she's using. She probably has one more zoom lense in her camera bag that would cover the 18-70mm range; so she can handle every standard wedding photo with her equipment. If you can afford the high price of her gear, then you will be optimizing the end results. But I have a suggestion: Start with a Nikon D80 and get two lenses for it from eBay - a Nikon 18-70mm Digital Lense and a Tamron 28-200mm film lense. All of this will cost about what she paid for her 70-300 Canon lense and will deliver outstanding sharpness and quick autofocus.
The Tamron 28-200 film lense when used on the Nikon D80 converts to a 55-480mm lense, which means you will have an 18-480mm range with just two lenses. For a flash, I recommend a Vivitar 283 with a Quantum battery pack (good for 350 images on one charge), and you'll need an accessory hot shoe with a pc post. Get a three foot pc cord so you can use the flash off camera.
Hope this helps!
Michael