I've read that the pre-order items will be available for the head start. Is that when a link for them will appear in my account? There isn't a link to apply the pre-order package at present.

I've actually heard the opposite. That the items couldn't be made available for the head start, but will become available on the 22nd, when the game is officially released (or on the 25th if you're in Europe). But, I could be completely wrong! (And I hope I am!) =)