I can use social media as a professional in various ways. I can connect with organizations of interest that can help me improve my teaching skills. I can follow various professional that I might think have special skills that I can learn from. I can also share my own classroom work and ideas and connect with other classes around the world. Things to consider is the authenticity of whomever I am following, Will I actually benefit from their skills? How much of my classroom do I share without sharing too much?
If I came across an inappropriate post from a student in my class, I would address it by directing it to the principal. In the past I have had students tell me, and show me inappropriate posts from other students. I have consulted with my principal and he has dealt with it. It's not that I am avoiding the issue, I thank the student for sharing and I let them know that we will help with the issue. But, my principal is trained to handle social media issues, bullying, etc., and I have full confidence that he will take care of it, and he has many times.