Does that mean 1 DLC purchase can be used by every profile on the console?
No. When you purchase a DLC for a game or a game it self that you bought via Xbox Live from your corresponding Xbox Live account, you are the only one have access to it, and no one can even it is on your hard drive, whether it be Xbox 360 or Xbox One it cannot be used by another Xbox Live subscriber. On the other hand, if there is family sharing feature enabled, it may work, yet I do not know how family sharing actually works, really.
False. You can share content with other users. for this is done very often with many games. I have friends that have only ever once downloaded the BO2 maps for one account yet have several child accounts that can play on the maps as well.
I think the DLC is locked to the console and that everyone on the console can use it.
Nah, you can move it between consoles as well. Just the person who bought it has to download it to that console, not just copy it. I have a friend that does this so their son can play the maps on a different console while they play a different game on theirs.
when you buy something the license/rights is on your gamertag and on the first console it was downloaded to.
example I buy bacon gun skin on my xbox with my gamertag
my brother can use the bacon gun skin on my xbox with his gamertag.
...Avatar clothes are the only things that are exclusive to one gamertag