I don't want to know what celebrity A had for breakfast. But if celebrity A breaks a law or is abusive or is a wonderful person, then I would like to read about that in the news. We have to put up with all their promotions when it benefits them, so I think we should be able to read about them when it isn't entirely beneficial too.
When a person becomes famous, they give up their right to privacy. If a person is interested in a celebrity's work, they might be interested in personal things about the celebrity, too. For this reason, it's fair to publish information about the celebrity's personal life. Also, if a person misbehaves, people might want to stop supporting that person professionally.
No. the things that celebrities do in their private lives should not be newsworthy unless it is the type of celebrity who tries to get attention. Celebrities deserve some privacy, however, some celebrities seek media attention in order to remain famous. If the celebrity seeks attention than all news about them is fair game.
A celebrities life is no different than our own, and everyone has things that they'd rather keep private. However, people seem to forget this when it comes to public figures, and for some reason feel entitled to every detail in their lives. I'm totally against this, and think this whole celebrity worship culture needs to end.