Few questions about Twitter, answer please?

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1. How do you contact someone that isn't following you on Twitter?Don't tell me ask them to follow you!How can I email/contact them if there isn't a message option?Or at least how do I make them see my tweets?
2. When someone posts a tweet, and others reply to it can I see the reply?If so, how can I see the reply that others posted?
3. How do you stop someone from following you without blocking them?
4. If you set your tweets to private, does this mean no one can see it even the people that are following you and the people you follow?Or can the people who follow you and the people you follow still can see your tweets?