Many people use twitter, including me. To be honest, I use twitter to stalk celebrities, and yes some do reply to you. It's like the lottery, it will happen. Tweeting something new is easy, you just tweet whatever comes to mind.
Overall, I don't really get your question, so hope that helped.
Twitter is popular because you can connect with your favorite celebrities.
They usually do on things like facebook,twitter,MSN is because, they think its cool and there get something out of it but its not that good when there's loads of people imitating.
Because theyr'e celebrities and they sometimes have to keep up with theyr'e people
They are celebrities because they have a special talent, or they are really good at something. That's how someone becomes a celebrity.
in my opinion, it isnt because you can follow celebrities and see what they are getting up to, and you can also follow your friends if they have witter :)
Because it's good for talking to your friends (and even celebrities) and you can find out news and other interesting information on there.
You can never be sure they are who they say they are unless you do something like make them follow you on twitter because you cant just ask a personal question they could just look it up. The only way really is you win a link or a pass from their official page.
A Social Networking site in which members post short 'updates' where they say what they're doing at that particular moment. People like it because they can get updates and news from celebrities
I'm pretty sure there isn't a limit because some celebrities are following over 100 000 people. But if you follow many people at once (I'm not sure what the hourly limit is) you will have to wait an hour until you can follow any more.
Society is obsessed with celebrities and fame because they have something that society usually does not. They are able to make money and get free things simply because they're famous while most of society is homeless or unemployed.
Because everybody wants something from them. This can be overwhelming for celebrities, so they tend to stay away from the real world so they can have privacy.
because twitter is not that popular.