One way could be if someone shares their story to a group chat or directly with you. But this is dependent on others' actions and not a guaranteed method.
Yes, you can. Check for things like the way the image is cropped. Instagram stories are usually in a specific aspect ratio. If the screenshot has that same ratio and there are elements that seem to be part of an Instagram story's interface, like the bar at the top or bottom that might have been partially cut off in the screenshot, it could be from an Instagram story. But again, it's not foolproof as some editing can be done.
You can't watch Instagram stories secretly. Instagram has privacy settings for a reason, and trying to bypass them is unethical and might lead to account suspension or other penalties.
If it's on a social media platform where the graphic novel has an official page, you can usually go to the page and look for the 'unfollow' button. It's often near the 'follow' or 'like' button.
It could mean to stop following or subscribing to updates related to a graphic novel. For example, if you were following an artist or a series on a social media platform or a website dedicated to graphic novels, 'unfollow' would be the action of disengaging from those updates.
Well, to unfollow stories on WhatsApp, first, make sure you're in the app. Then, look for the Status tab. Once there, you'll see the stories. Long-press on the story of the person you want to unfollow, and you should see an 'Unfollow' option. Click that, and you're done.