[cleeve]

1. Lee A Stewart answered it pretty well up above. Apple TV and Movies Anywhere will take up probably ~25-35% more data than Disney+ or Netflix, as they run at a higher bitrate (but also look better).

2. You'll have to be paying for the 4K package of whatever app you're using, but on any half-decent modern 4K TV, the apps should stream in 4K.

3. The purists here will probably try to argue otherwise, but 4K streaming from the best platforms (Apple TV & Movies Anywhere) is probably 90% as good as 4K disc based content from a picture quality perspective. Vincent Teoh of HDTVTest and others have done side-by-side testing, and they look virtually identical at a standard viewing distance. Sound, however, is a different story. If you've spent thousands on a nice Atmos sound system, you probably don't want to go with streaming as your primary way of watching content. And again, it depends on the platform. Google Play and Amazon Prime are pretty sub-par for 4K streaming, Netflix and Disney+ are middle of the pack, and Apple TV and Movies Anywhere sit on top.