I have questions about sending letters to celebrities...?!

I have questions about sending letters to celebrities...?

Okay, I'm a huge fan of the Harry Potter films. I REALLY REALLY want to send a letter to some of them (Probably Dan, Emma, Rupert, and Gary Oldman-he plays Sirius Black). I don't know what to say though, so if you could help me with that. I also really want to get an autographed picture, so do I just ask for that in the letter as well? Will they respond? I have read on a site with the addresses of the actors that Emma will always respond to letters, and has her family and friends help her with it. What kinds of responses do you get if you send a letter? Also, a dumb question, but should I hand-write the letter or type it up and then put it into the envelope? Also, is it a bad idea to send a letter to Dan-because I'm sure it gets very hectic with all these letters coming in. Sorry, so many questions, but if you have any additional details I would like to hear about them!!!

Always hand write your letters if you want a autograph not typing because that is too impersonal, best write to the film company and always be polite.
Success!