After going through all the information and quote from as many different official Microsoft sources as I could find, these are the answers we currently have to these key questions.
Does it require an internet connection?YES. Xbox One will need to connect to the internet frequently in order to let you play games, watch TV or do anything else. According to Microsoft's Phil Harrison it will need to do so approximately every 24 hours at least, more frequently for games and services that rely more heavily on the cloud. If you are somewhere without any Internet connection at all, such as a military base, you will NOT be able to use Xbox One.
It is reasonable to infer from this, and the other information Microsoft has provided regarding game-sharing, that Xbox One will need to connect to the Internet to authenticate you as well as connect to the Cloud. Games appear to be tied to your Xbox Live account, so without connecting to the Internet the Xbox One won't be able to verify that you own them.
Is it always-online?Technically NO, but it depends on your definition of the phrase. You will be able to watch TV and Blu-Ray movies and play single-player games without being connected to the Internet at all times, but as outlined above, the console will need access to the Internet at least once a day. Microsoft's Harrison phrased it thus, speaking to Eurogamer: "Some bits of the system will work offline. I think the key point to make is that Xbox One requires an internet connection, but it does not need to be connected all the time. We think that most of the biggest games on Xbox One and most of the games and experiences and services you want to use will be internet-connected."
Can I play my friend's games on my console?NO, not unless you're signed in as them. Otherwise you will have to pay, full-price, to access that game. The clearest stance on this comes from Eurogamer's interview with Harrison: "I can come to your house and I can put the disc into your machine and I can sign in as me and we can play the game. The bits are on your hard drive. At the end of the play session, when I take my disc home - or even if I leave it with you - if you want to continue to play that game [on your profile] then you have to pay for it. The bits are already on your hard drive, so it's just a question of going to our [online] store and buying the game, and then it's instantly available to play. The bits that are on the disc, I can give to anybody else, but if we both want to play it at the same time, we both have to own it. That's no different to how discs operate today."
Microsoft's Major Nelson (Larry Hyrb) put it this way: "Should you choose to play your game at your friend’s house, there is no fee to play that game while you are signed in to your profile." But then if you go home and leave the disc with your friend, they will have to pay for that game if they want to play it on their own profile.
What about members of my family on the same console?YES. If a game is installed on a console, anybody who uses that console can play it through that console's parental controls. But what we don't know is how many accounts this will apply to: four? Five? Two?
Bottom line: you can only share games if your accounts are on the same console and parental controls are set up to do so.
Can it play pre-owned games?YES, but we don't know how, and Microsoft isn't saying. It's likely to be based on a license system. The official Xbox One FAQ is brief on this issue: "We are designing Xbox One to enable customers to trade in and resell games. We’ll have more details to share later." That has been echoed since by Harrison and Hyrb.
So you will be able to trade in games both at retail and through some kind of online service, but we're not likely to get the details on exactly how that works for some time yet.
What about game disc-rental services like Lovefilm and Gamefly?That's obviously going to be affected, but we don't yet know how.
Does every game have to be installed?YES. This is partly down to the speed of Blu-Ray drives. If you want to play a game, it will have to be installed on that system.
How big is the hard drive?500GB, but you can't use all of it. Microsoft's official Xbox One information site contains a significant caveat in the small print: "Xbox One system software uses a significant amount of storage; less internal storage will be available to users."
Will it work without Kinect?NO. Xbox's UK marketing director Harvey Eagle said at last night's Microsoft-hosted stream that Kinect requires to be attached to the console in all cases, and this has since been echoed elsewhere. "The all new Kinect is now an essential and integrated part of the platform. By having it as a consistent part of every Xbox One, game and entertainment creators can build experiences that assume the availability of voice, gesture and natural sensing, leading to unrivaled ease of use, premium experiences and interactivity for you," says Microsoft's Xbox One FAQ.
However, developers will not be mandated to use Kinect in every game, Phil Harrison clarified to Eurogamer. Another nugget of information: you also can't turn off Kinect's microphone, says hardware program manager John Link (via Polygon). It's always listening.
Will all that live TV stuff be available outside of the US at launch?NO. At launch it will only work in the US, with a gradual global rollout planned.
How will Xbox One's live TV work with existing cable providers, like Sky?DON'T KNOW. No Microsoft source has been clear on this - both Harrison and UK marketing director Harvey Eagle have stated that this will be revealed in due course. It's likely that all the requisite agreements are not in place yet. Xbox.com's own Xbox One information suggests that eventually it will work with any TV-viewing box via HDMI pass-thru: "Connect your cable or satellite box to your Xbox One and prepare for lift off."
Is it backwards compatible in any way?NO. Not with any Xbox 360 games, digital or physical. "The system is based on a different core architecture, so back-compat doesn't really work from that perspective," according to Xbox Live vice president Marc Whitten.
Will my Xbox Live Gold account transfer?YES, says the Xbox One FAQ: "You do not need to buy a new Xbox Live Gold membership. Your current membership will work on both Xbox 360 and Xbox One."
How about my Gamerscore?YES, that's coming with you as well - along with your Avatar. "All of the gaming identity that you have on Xbox 360 will be there on Xbox One as well," said Harvey Eagle.
And my digital games library?NO. You'll have to say goodbye to your Xbox Live Arcade purchases, as outlined by Eagle last night. But entertainment purchases WILL transfer over.
Will I still have to pay for Xbox Live Gold?YES. The head of Xbox in Europe told The Metro: "Yes, we still see that as a chargeable service... I think that people understand that for a premium service that gives access to so many different rich parts of entertainment. Our consumers are happy and I think we represent great value there actually. If you look at the plethora of things available now through Xbox Live, particularly the Gold service and what we put behind Gold, we’ve got no plans to change that."