User blog comment:Sperez2012/Earth DLC Characters/@comment-3444770-20120718130306/@comment-4618888-20120718130953

If you have downloaded and installed the DLC, you will have a chance of receiving the Earth characters, weapons, mods, and gear. (Note that I said a chance, not a guarantee...) If you're on Xbox, you can delete the other DLC and keep only the Earth DLC installed when buying multiple packs to increase your chances, then download the others again when you want to play matches (can't do this on PC or PS3).

The store descriptions do not change with DLC--only occasionally do they do so when the weekly multiplayer balance changes are applied.