In the UK:
JK Rowling
c/o Bloomsbury Publishing Place
38 Soho Square
London W1V 5DF
England
In the US
JK Rowling
c/o Scholastic Books
555 Broadway
New York, NY 10012
USA
No, Ms. Rowling doesn't read every single letter she recieves. I believe there is someone who "screens" her mail.
Ok, here is where you can learn everything you ever wanted to know about your favorite author.
Among numerous awards, Joanne Kathleen Rowling has won the 1999 American Booksellers Award, the British Children’s Book Award of 1999 and 2000, and the Smarties Prize. As of 1999, book rights had been sold to England, U.S.A., France, Germany, Italy, Holland, Greece, Finland, Denmark, Spain, Sweden, Iran, Iraq, Canada, and Mexico. Also, there was never a larger first printing of a book in history since Harry Potter and the Goblet of Fire. 3.8 million copies were printed in the U.S.A. alone.
Here are some links to other areas giving information about Rowling.
This is an 8-page school report I wrote about Rowling. I'm relatively sure that all of the information is true, but there were many online sources. Your browser should put you into a microsoft word document when you click on a link.
This site is NOT affiliated with J.K. Rowling, Mary Grand Pre, Scholastic, Bloomsbury, or any other Official Harry Potter company. It is purely a fan site.