I currently own MCC and Halo 5. I am looking to get Halo Reach to add to my Halo Collection. I have seen it is available in Xbox Store on XB1. Question is if I purchased a physical version instead of digital would it still work on XB1. Many Thanks.
Yes that will still work ok, as long as it’s a backwards compatible title it should work fine on your Xbox 
Putting the disc in your XB1 confirms that you own it and will start the download from the Store. From there on out, you’ll just need to pop it in whenever you want to play it. You’ll also need to download any DLC seperately after the game installs, where you’ll want to go to “Manage Game” and it should have your applicable DLC listed.
Sometimes after the initial install, the game will freeze up and not boot. All you have to do to fix this is uninstall and reinstall once, and your problem should cease to occur.
Thankyou for your help. Very much appreciated.