First off, you will keep your progress, no matter what. It's all stored on Bungie's servers, so as long as you're on the same profile, you'll have access to your characters. Second, all dlc is digital. Every Destiny disc, regardless of the version, only contains the base game. Third, DO NOT BUY A DISC VERSION OF RISE OF IRON!! The physical copies come with codes for the expansions, but those codes have all expired. The only way to guarantee you get working versions of the expansions is to buy them digitally. Finally, you should be able to buy ROI digitally by itself, if you have the other expansions already, but you can also get a bundle that includes the entire game. I know you said you want to use a disc, but there is absolutely no advantage to doing so. All modern console games have to be installed to your hard drive, and then the disc is just used to prove you own the game. The disc is never read to access any game content after the game is installed. With a digital copy, it verifies your ownership online. Now, if your internet were to go out, you might not be able to play a digital game, as it wouldn't be able to verify that you own it, but Destiny is an online-only game, so if your internet is out, you wouldn't be able to play it, whether you're using a disc, or digital copy.