Very thoughtfully written.
Personally, I'm not going to sign. I already use legal alternatives to get my music -
Royalty Free music downloads | Jamendo - Jamendo
Online Music, Music Downloads, Streaming Music from Magnatune
I'm not as demanding with movies and am happy with what I can get already for free, legally, on my mobile phone. As for music, I've simply given up on the RIAA and my boycott of them has simply turned into a full walkaway, but I wish you success with your endeavor.
I would offer some constructive criticism if you're open to it.
Your petition is also a survey. I think when you try to make two things into one thing, it's harder for people. You also are trying to perform your own validation and I think many people will not be willing to give you their email address.
Maybe consider instead a free online petition - here's one but there are others -
iPetitions - Online petition - Free petitions
The petition I signed for HTC to unlock bootloaders was online and free and people could sign it, or sign it via Facebook or Twitter - I signed via Twitter, in, out, boom, done.
There are also free online survey sites. You could do both and mention each one in the other.
Best luck!