The Service Config ID, and Title ID appear under the Xbox Live services, which I don’t have at this time (at least I don’t think I have it).
As for sizes, both total package size and memory size, it is my understanding that UWP applications are limited to half the Xbox One memory. That would be roughly 480MB but I’m not certain of it. For the total package size, my game stands at roughly 7.5GB, and I don’t know if Windows Store has limits that will prevent the upload of my game. I can easily separate out each level, and load them asynchronously but I’m not sure if I’m going to hit the RAM limit.
Under the Windows Developer Dashboard, there is an Add On for the packages, but I’m not sure if the API for accessing them through a game is there or is it done via a separate process by gamers, meaning code would be needed to locate downloaded content.
Personally I’m at a fork: focus on Steam, which has the SDK part of the UE4 environment, has no limitations, and is well documented; or develop for UWP, under the Windows Store, both of which are questionable at this time (UWP, MS Store).
Given these limitations, I’m returning back to Steam, and then I’ll look at UWP again.