I'm Not too sure how the system works but I get one of those emails (similar) every month because I pay monthly.
I suspect that it’s just a reminder to let you know that it has been 12 months since you last donated.
Again, I’m not too sure about the extras. I only know as much as everyone else. After you have donated your username gets added to the “Donater” list.
See here and I presume, after 12 months it gets removed.