provided its the PC version, you should be set. Once installed, all PCs versions are identical.
That is not true.
D2D's .exe file of Oblivion is not the disc or Setam .exe and because of that, modders have difficulty with it (Script Extender especially).
Not being offensive here, but please don't give out false information.
OP, if you don't wanna wait for your disc, get it on Steam. Skyrim's a Steamworks title as it is. I'd avoid clients like D2D UNLESS you're somehow able to buy it through D2D, but activate through Steam.