The impact could be positive. If the story is inspiring, it might encourage your friend to be more selfless or more committed to their beliefs. For example, if it's about a missionary who helped a lot of people in a poor area, your friend could be motivated to do some volunteer work.
You could start by creating some suspense. For example, say something like 'I've got a story that will blow your mind' before you start. Then, tell the story in a vivid way, using lots of descriptive words.
The best way to do it is to get your friend's okay. After that, you can pick out the most interesting parts of the story and describe them vividly in your story. Just be careful to keep the essence and the main message intact.
Yes, in many cases you can. There are certain story quests where you can team up with your friends. However, some main story quests might have restrictions, especially those that are more focused on the individual character's story development. But for a good portion of the side - story and some group - oriented main story parts, joining friends is possible.
It depends on the privacy settings of your story. If your story is set to public, they may still be able to see it even after you remove them as a friend. But if your story is set to be visible only to friends, then once you remove them, they should not be able to see your story.
You can share a story with your friend by having a phone call and sharing it during the conversation. Or, if you both like reading, you could make a little booklet of the story and give it to them as a surprise.
Unfortunately, once your friend has viewed your story, there's no option to unview. It's like opening a door and not being able to close it again in this case.
I have a friend who loves to perform. In a restaurant, he suddenly started singing a song. Everyone was looking at him. At first, I was a bit shocked, but then I joined him. The restaurant manager was so nice that he didn't stop us. Instead, he gave us a free dessert. It was a really fun experience.