1 it depends on the size of the card you use.
2 if the video gets to long of a file, it will stop the file and start a new one, seamlessly. they just have to be "joined" in an editing program, GoPro's work the same way. The length of the video recorded depends on the resolution you set the camera for.
3 I love this camera, we have a T6i, 80D, and a few GoPro's, the 80D is my go to for all around use.
Canon - EOS 80D DSLR Camera with EF-S 18-135mm Lens Video Creator Kit - Black
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Canon - EOS Rebel T6i DSLR Camera with EF-S 18-55mm STM Lens Video Creator Kit - Black
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