I am using ACR2.4 which does not have camera profiles etc. so your comments may not be valid in my case.
The process to make custom camera profiles for ACR uses a Macbeth color checker, DNG software from Adobe Labs and controlled lighting. Complete information is here
I would also say that producing a custom camera profile for ACR is similar to make custom Canon Picture Styles. The two methods are very different, but the result (more accurate color and tonal scales, or customized alternative imaging) is the end to both methods.
do you save your adjustments in the RAW file in DPP or as a recipe? I was not 100% sold on the idea of saving the changes data back to the original RAW file, I know its not changing the RAW data just tagging the data for the changes but I wonder about the possibilities of data corruption happening when saving to the RAW file.
I always save my approved changes to the files. You are correct that the raw data is not affected, but I find this method more efficient than using a separate file (like ACR).
I also think the chances of data corruption when using this method are no greater than when using ACR or any other raw processor.