The Deer Hunter 4K:
1. One of my many favourites and the picture is pristine. Definitely worth the upgrade if you're a fan.
2. Comes with the 4K, BD (not sure if it's Region B locked), another BD of extras, CD soundtrack (fidelity is OK). Here's the link:
https://www.amazon.co.uk/gp/product/B07DDFX43H/ref=oh_aui_search_detailpage?ie=UTF8&psc=1
3. Audio on the disc menu says it's 6 Channel Dolby Stereo with the disclaimer that they tried their best to approximate how it sounded in cinemas back in '78.
4. Pressing Display on the Sony states the audio is DTS-MA 5.1 and it sounds fine. Surround action is pretty much limited to the score and crowds.
5. Really good separation between fronts/centre with Cavatina's guitar in the centre and strings in fronts during opening credits with more surround action on the closing credits.