As I understand (could be horribly wrong), Retropie is a trimmed down version of Raspbian with an emulationstation frontend and some emulator cores.

Is there a way to have all of this with the full Raspbian front/back end to toy around with lxde and other things that the rPi offers. (I want to be able to use the rPi with several things including RetroPie, RaspBMC/OpenELEC, and do some basic computer things in the raspbian gui/terminal.)

Possibly this tutorial?

RetroPie-Setup: An initialization script for RetroArch on the Raspberry Pi

Does this work with an rPi 2?

Do I need to make any changes to RetroPie to be able to do this?