Lightroom IS Camera RAW. Well, it is built upon it. All of Camera RAW functions exist in Lightroom, and the RAW conversion is identical code. Of course, there is more to Lightroom than Camera RAW itself provides, just as there is more that Photoshop offers over Lightroom.
If you are looking for RAW conversion, then Lightroom and Camera RAW in Photoshop are identical.
Rather than use Camera RAW, I use Lightroom as my primary photo tool. If there is some task that I need Photoshop for, I will simply select "Edit in Photoshop" from Lightroom, and I am taken into the Photoshop interface. Camera RAW is not needed, as Lightroom passes the file to Photoshop as a .psd or .tif, depending on your setting. After I am finished with my edit, I can close Photoshop and return to Lightroom, with my edited file intact, for completion in Lightroom.
Edit: in response to your question about Adobe Bridge: I have never taken to Bridge, but as far as arranging, tagging, rating photos functions in Bridge: those functions are available in Lightroom as well. In my opinion, LR provides many more functions, but also superior ease of use to Bridge.
For anyone wishing to compare LR to Photoshop, I encourage you to simply download the 30 day trial of Lightroom and give it a spin.