Communication's completed a huge curve of development and returned to a medium that drives brevity and encourages short cuts, leaving little room for chatty content. That said, it's become an art from that's produced some classic tweets that come close to Hemingway's famous, poignant six-word story: "Baby shoes for sale, never worn."
I doubt very much that Banks is a homophobe. She has worked with many gay artists and is bisexual herself. But the fact that sales of her music have risen sharply since her tweet to Perez Hilton probably suggests that she won't be admonishing the homophobic members of her fan base any time soon... We all know that freedom of speech is fundamental to any democratic society. If you want to say the word "faggot" you are free to do so, but you should also accept the consequences.
One of the downsides of being a "celebrity" Tweeter is the preponderance of people who seem to hang about in dingy bedrooms in their dirty underwear "trolling". A troll is somebody who sends abusive tweets, often to celebrities- some are simply negative comments on a career, others are far more abusive and personal. Accepted practice is "do not feed the trolls". The general feeling is that these low-lives need the attention and that by replying or interacting with them you are giving them what they want. I beg to differ.
Trolling is the stuff of internet myth and legend. Using the internet as a platform, the troll is a person that will go out of their way to try and spark an argument by making deliberately stupid or offensive comments, safe in the knowledge that they are out of harm's reach. And, to be fair, it can be hilarious if done well, spiting the everyday internet user into an all out rage in a very public way for the entertainment of many.