Smart Objects

I did this within LR using the adjustment brush...I've never used Smart Objects...could I open this into CS6 as a Smart Object, make an easy selection then redo the adjustment brush activity to a more normal appearance?

I don't use LR, but this should work the same as using ACR. Open as a Smart Object. Right click and choose New Smart Object via Copy. Make the copied SO the active layer. Make your selection and add a mask. Double click on the copied SO which should take you back to LR (it goes back to ACR), make your adjustments, and click OK when done. It should show the adjustments on the copied SO.

Yes if you open it to PS as a Smart Object you could re-edit it, although it would be in ACR not LR. What you have to remember though is that by embeding it as a SO you are effectivly embedding the whole RAW file inside the .PSD/TIFF. This does mean that the original file in LR stays the same.

Alan