My understanding is that when you purchase Minecraft (#1 game wOOt) there will be a redeemable code. Because DLC stands for downLoadable content. You will have to be connected to Xbox Live but you can create a free silver account. Doesn't require gold membership to redeem the code.
To sum it up
- You do need an internet connection
- you need a silver account (free account) <--- http://www.ehow.com/how_6315762_set-xbox-live-silver-membership.html
- you do NOT need a gold membership!