I play Skyrim on an xbox. I would like to delete dawnguard for a while so that I don't have to put up with the vampire attacks on a new character I want to make. My question is: if I delete it, will I be able to download it again for free? Would it be possible to move it to a flash drive, delete it, and then move it back when I wanted to play the content again? How do you move files on an xbox? Thanks.

If you delete it, you will be able to download it again from Live. Once you purchase any content, for any game, you can re-download it again for no charge.

Configuring a USB stick for storage for the Xbox: http://support.xbox.com/en-US/xbox-360/accessories/usb-flash-drive
Moving content from the Xbox to USB stick: http://support.xbox.com/en-US/games/xbox-games/manage-games-data

Edit: Grammar correction.

Thank you. No more dawnguard for a while then.

You're quite welcome, friend.