An axonometric diagram exists for Stratford (actually, there are two -- one for the platform levels and one for the subway levels). I'm not sure why they weren't included in the Freedom of Information response; it could have been for security reasons.
Parts of the station are owned by Network Rail, parts are owned by TfL who manages the overall station (but there are also staff from the individual train operating companies).
The TfL station layout covers the entire station, and shows which parts are owned by TfL and which aren't.
