I'm won't be touching the more specific questions.

All good questions though.
But chewing the fat on the more general questions above... I cringe at the methodology CIG are using. And the way I see it they have two main issues (and many others):
1. They're planning about 400 planets/moons across their 100 systems. Assuming those textures/terrain can't be part of the downloaded client software, that's a ridiculous amount of continuous streaming / bandwidth. It will be interesting to see if some of that data is held in local (client) data caches, eg. a player's most common or recently visited planets fetched from local SSD.
2. Their multiplayer networking is server-client, another huge bandwidth resource hog.
My engineering teeth are clenching just thinking about the running costs. But this will all be necessary to deliver CRobber levels of fidelity. They can't use pure procgen for planet generation and expect to do what they promise. But all that streaming data and running costs... although cost may not be a factor if their funding model continues to-the-moon (cough cough).
Looking at ED on the other hand, and again from an engineering perspective, ED does it exactly as I would do it, lean and efficient. The planet procgen is all performed client side, and the multiplayer networking is P2P. I know players hate P2P , but it's unjustly maligned IMHO. Handing over all that work (and most of the bandwidth costs) to the clients is exactly the solution I'd be considering in a first design, and only ditching it if more performant methods are needed.