Hi Megs!
First off welcome to the boards! I hope you have a lot of fun here. We're all here to help and your questions aren't silly.
I was wondering what Via Venue is? or if it is possible to write to an entire cast, like the cast of Eclipse
Via Venue is sending to a celeb on a movie set or at a concert etc. Via the venue that they are performing at. Although, you may not have luck with Eclipse as I've read that the studio doesn't pass along fan mail. You may have better luck trying each cast member individually.
And, is it possible to send a picture of possibly Edward and Bella to, say Kristen Stewart (

), and when/if it comes back signed then could you turn around and send it to Robert Pattinson ( {love} ) to sign also?
Yes it would be possible. However, if the autograph is valuable to you, you might want to rethink sending it. When you send things for celebs to sign, be aware that you may never see that item again. I always say, a general rule of thumb is never send anything you aren't willing to loose.
If you have any more questions feel free to ask!
Good luck!
~Annie
