Focus on a single object or thought for as long as possible, after practice it will be second nature.
Meditation can be done anywhere anytime in just about any situation. A method would be to practice compartmentalization.
No not necessarily given that everyone is different.
Yes, meditation has helped me though I’ve never really been an anxious person. It’s helped having a clear mind before a task with work or businesses meetings.
The evidence would be a personal experience.
One doesn’t need to be taught by anyone or go on meditation retreat. Can start with small simple steps, like when laying down before sleep. The way to clear the mind is to concentrate/focus on a singular. When one becomes more accustomed, then they’ll be doing it often on somewhat of a subconscious level.