A couple of months ago I started the development of a project called “The Twisted London Underground Map“. All the lines of the tube were included on it, but not the DLR nor the Overground. Today I finished an annex to that map that features the Overground at its full, including the to-be-opened Surrey Quays-Clapham Junction corridor.
You can check out the full-sized version here. As it looks (kind of) like the popular japanese weapon, I called it The Shuriken.
3 I don't think the data is available anywhere, sorry. Even my visualization doesn't reflect the whole trip. It just reflects what I could capture from the moment my program was ready to put points on a map.