You'll want a large aperture lens with a medium telephoto distance to replicate her photos. She lists her equipment in an interview and she appears to do a lot of her work with a 50mm f/1.4 and an 85mm f/1.8. Those are going to give you the look of the photographer you linked - in terms of the shallow depth of focus. But she is using a full frame camera, so you're going to have a tough time replicating her very shallow DoF shots on your cropped sensor Rebel.

If you're really digging her look and trying to replicate it - throw out any flash and artificial lighting - she's a natural light photographer. She bills herself as such and doesn't list any flash equipment among her equipment. She'll be using diffusing material or naturally diffuse light to create that soft light (soft light is the term for the long falloff off her shadows on the subjects). Think bed sheets, big windows with translucent blinds, cloudy days, shade from trees, etc. That soft look is a partly large aperture and partly soft light.

If she's doing Photoshop to make it softer (which it doesn't really look like she is much to me), you can try reducing clarity as @Steve Ross mentions or try one of the digital soft focus techniques here.

Baby photography (one of the big specialties of that particular photographer) is kind of a whole other world, so there's a bit more than just the right equipment. You'll need to be flexible, patient, have a plan - but be willing to adapt. Newborns have particularly splotchy skin so that's one reason you see alot of black and white there. Cute outfits and hats work to help 'deal' with some of their features that may not be quite in normal proportions yet.