I don't know anything about Smart Objects,never having worked with them,but I can answer the second.
In Bridge, you can right-click on the icon in the upper-right portion of your Camera Raw image, select Develop Settings > Clear settings to return the image to the original unadjusted state.
Develop Settings is also under Bridge's Edit menu.
Ok, I also noticed If you Right-Click at your Raw Image Inside the Adobe Bridge, and choose the: Develop Setting- Camera Raw Defaults, It dose exactly the same as using Develop Settings-Clear Setting. I did not see any other Different's..
What Is the different between Clear Setting, and Camera Raw Defaults ?
Clear removes the Camera raw settings completely. You will not see the adjustment icon on the thumbnail in Bridge
Camera Raw Defaults will show the icon and double clicking the thumbnail will always open it in Camera Raw with the Default settings. The Default is "As Shot", which is why you don't see any difference. It's when you choose a Custom Default that you will. It will stay with the Camera Raw file.
See this article by Julienne Kost.
Another difference is with Jpegs. Open a Jpeg in ACR, make an adjustment, click "Done". Select "Camera Raw Defaults" and it will always open in ACR instead of Photoshop. Select "Clear" and it's a normal jpeg that will once again open in Photoshop.
Basically that's about all I know, I normally don't use ACR much.