What’s the deal with flare ups?

I’m experiencing my first “flare up” and I have some questions: 1. Are flare-ups something that I’ll be dealing with for the rest of my life? Like in ten years from now, will I still be getting flare ups? 2. What exactly causes flare ups- is it a lack of sleep, poor diet, physical stress, emotional stress, or is it completely random? 3. When you first feel the flare-up starting, are you doomed, or if you rest a lot and prioritize a healthy diet right away can you stop the flare up? 4. Are you contagious during a flare up? 5. What’s the deal with the stories I hear about people developing CFS or autoimmune diseases from EBV? Is this true, and is there anything that I can do to avoid this?