Keto diet questions

Hi everyone! These are my questions about Keto Diet:

1. What is the keto diet and how does it affect weight loss (including ketosis)
2. . Is the keto diet safe for me, and are there any risks?
3.  What foods can I eat on keto, and what should I avoid?
4.  How many carbs can I have on keto, and how do I know if I'm in ketosis?
5. . What are the common challenges of starting keto, and how can I overcome them?
6.  Can the keto diet help with some specific health conditions?
7.  Should I talk to my doctor before starting keto?
8. Is there a more suitable age to start it?