I use the grading a lot. Simple to use but effective. Usually in a series of subs there will be a few that are of distinctly inferior quality to the others. If this is the case it helps your final integration if you remove those. The grader makes this easy. Don't just remove the worst few. All the scores relate only to the current set so are completely relative. They may all be quite good do none should be removed.
I have a Canon 6D also and it takes about 9 seconds to download each image on my setup which would total 1.5 minutes for 10, a lot quicker that you are seeing. Did you check the "Use high speed download" on the Camera tab of the Control Panel? You can find a lot of info about the run in the log file found in this directory:
C:\Users\jerry\AppData\Local\SequenceGenerator
It includes info on the time some processes take.
I never tried to use the wifi and it is apparently not supported, and I have not tried to use liveview, but will be doing so shortly.