Few questions about Twitter, answer please?

[507]

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?

[NHK]

1. You just '@' them, or direct message them.
2. I'm pretty sure you will see the replies to someone else's tweet only if you are following that person. So if I write something on twitter, and five people respond to that tweet, the only way you will see it in your time line is if you are following me, or one of those five people.
3. You block them, or you ask them to stop following you.
4. Only the people who follow you will be able to see your tweets if you set your profile to private