Well, it really varies. Some platforms enable you to share stories on your story without much restriction as long as it complies with their community guidelines. However, if it's a more professional or work - related platform, there might be limitations or it might not even be a feature at all. So, you need to check the specific rules of the platform you're using.
Yes, on some platforms you can. For instance, on WhatsApp, you can share a status which is like a story, and you can choose to share it within a specific group. It's a convenient way to communicate something quickly to a group of people.
Yes, usually you can share your post to your story. Most social media platforms have this functionality. However, it may depend on the privacy settings of your post and the specific rules of the platform.
First, make sure you have the right to share. You could summarize the main points of the other stories and blend them smoothly into yours, always acknowledging where they came from. Another way is to quote directly with proper attribution.