Please show me where it says that the downloaded song is exclusive to those who bought the five releases. I think it only says that it will be free for them. As in, other people will be able to buy it. I highly doubt that avex would lose an opportunity to sell something. In which case, I'll pay the $1.29 for the song on iTunes. I'm not that poor
And as far as the wallpapers. I haven't used an Ayu wallpaper in years. Plus, if I decided I wanted one, there members here at AHS that will make me a lovely customized one for free.
EDIT: Also, it looks like you only get to choose one of the three guaranteed gifts, not all three.