I'm about to sell my 360 and I have some games and a lot of DLC stored in the HDD. If I remove my account from the console but keep the games/DLC will the buyer still be able to access that content?
DLC Content has 2 licenses. One is to your account, the other is to the console it was purchased on. If you remove your Profile, and you purchased the games on that console they will have use of the games. If not then they will not have use of the game. Also the games are only usable until the original gamertag transfers the License to a new console. Or they format the drive or become corrupt. Xbox License Transfer Site - http://support.xbox.com/en-US/xbox-360/downloadable-content/download-content
That's not true nothing is account bonded it is bonded to the XBox 360's internal memory so what ever you had previously downloaded to that console can be accessed at any point and time by any profile however if you were to download it again to another console your profile would always have to be singed into XBox live for you or anyone else to use the DLC or previously downloaded games.
There is multiple ways to acess content be it games dlc themes etc. you can for one license transfer which transfer your item Id to a new console without having to be signed in to the account. This stays till someone decides license transfer to a diff console ( unless they don't download that specific item then it will stay active.) Then you can sogn into the account start up the target item (like a game for a dlc) with the account signed in then once you hit the main screen just sign out(note this does not work always and is a lengthy process)
No, not if you remove your profile from the XBox.
Games and DLC are mostly account bound, so to access it from another profile, you have to have your own profile saved on the console it was first downloaded on or sometimes even logged in as second player. This sometimes differs depending on content type, but generally you can use content from all profiles, when the profile that bought the content downloaded it first on said console and is still accessible. There's a way to transfer content licenses, but that only works from console to console, meaning it is account bound as well.