I think I owe an update on a couple of the discussion items I joined on this thread.

First, the auto mount issue does appear to be solved. Since the last update to INDI/Ekos, the Canon has not auto-mounted after I turned automount options off. THANKS for that, Jasem.

I had problems with the camera not shutting down as well. Same issue as mentioned before. I would close INDI, nothing was happening, no images being taken, etc. Yet when I turned the camera off, I got a message something about trying to upload an image or something and a big, blue spinning circle that just would not go away. Battery lid had to be opened to kill it (that scares me!).

So I played around and I discovered I could cause the problem by going into the INDI camera settings and attempting to upload the captures do the camera's SD card. the images go there OK, but when I do that I get the shutdown issue. I'm not at the Pi3 right now, but I believe the options are something like "Local, Client, Both" for that setting. As long as I leave it at default and save the images to my Pi3, there's not issue. But if I attempt to allow images to save to my camera's SD card, I was getting the shutdown problem.

Outside of that, the Canon 6D is working fine for me at this point. After I created a 2Gb swap file on my Pi3's SD card, I can now transport images in FITS or .cr2 without crashing or hanging. FITS images are sloooooooowwww but they work. I asked about using .cr2 files for astrometry since they actually download pretty quick and Jasem says he's working on that. I do all my processing with the RAW .cr2 files, so I really don't need the FITS transformation to happen.

I hope to get outside tonight and finally point all this stuff at the sky and see what happens!! Up till now, it's been all indoor testing.