Welcome to the forum. The majority of members shoot Canon or Nikon because for one, Canon and Nikon are the two leading camera manufacturers and have been for a long time. Another reason is brand loyalty and a big reason is lenses. Many members, like myself, shoot both Canon and Nikon. Other popular makes are Sony and Pentax and Olympus. Your Olympus is an excellent camera.
S1 is for normal operation and S2 is for panning and S3 is only active when you fully depress the shutter button.
BTW, welcome to the forum.
I just had a few issues with Canon customer service and in the end they made good.
Speculating what happened will solve nothing, you need to contact Canon during normal business hours and find out what the issue is and correct it.
I sent in a very expensive lens for repair and because someone made a data entry error, not only was the repair delayed but my credit cards were denied when I attempted to pay online for the repair. When I finally spoke to someone and got things resolved, the lens was repaired and shipped in 1 day.
Karma had nothing to do with it, just simple human error. Be patient, don't jump to conclusions, talk to a service rep and get the situation resolved.
How wide do you want to go? You already have the 18-55. If it were me I'd consolidate and get rid of the Sigma 70-300 and the two kit lenses and get the Nikkor 18-300 or the Tamron 18-400.
There's nothing wrong with your 18-55 lens. It may not be Canon's best but it isn't garbage either.
I shoot both canon and nikon so I have experience with both. The Canon EOS DSLR'S are easier to learn and use that the Nikons.
The 80D is an excellent camera, more suited to what you'd be using it for. Since it doesn't appear that you are interested in action photography, the 6D is also a good choice, but I believe your lenses are EF-S so they won't work on the 6D body.
Guess that mean we will have to wait a bit to buy the new camera, no big deal...
What does "knowing how to type" have to do with anything. If you know how to spell then your ready to go. I never learned how to type and basically that's what I do for a living. The guy at the next desk at work knows how to type but he can't code for crap. I am a very good coder but I need to pay attention to the keys. Given equal assignments, I would finish first because I know what to type.