Here is the full list of all 12 Hell Yeah! Wrath of the Dead Rabbit achievements worth 400 gamerscore.
You mission freak!
Congratulations! Thanks for your hard work!
You did it on purpose?
You got a full armoury!
Thanks for your help!
When you're the Boss, you have 365 birthdays.
Ooooh! Poor thing! Want a cookie?
You won the Grand Prize!
You are gifted, sir!
You can ride for hours!
Wow! All these fancy things!
Now's the time to strike back!