Tracing Walls, creating the 3D Building (Revit) from a 2D Imported plan (AutoCad)

Howzit guys!!!

I haven't been here in a while but am finally in need of some guidence! I'm not sure if this is even possible and I don't think it is; My company's busy with a HUGE HVAC project and I need to redraw the building in Revit MEP 2012 (2013's about to be loaded, if that makes a difference) but it seems or feels like I'm doing it the wrong or long way by clicking on every single 2D wall to create a 3D one... I figured the best way to do such a task was to first import the 2D Plan drawings from AutoCad (2012), set them at the correct heights, line em up and and then extrude. Well, I'm not really extruding as I've given the wall a height so basically all I'm doing is clicking on a 2D wall line and then to the next with an occasional trim here 'n there and there lies my problem: there're SO MANY!! I have to do this with each floor, Basement to 4th and reckon it's going to be quite time consuming, so my question is: Isn't there a quicker known method? Isn't it possible to say, select all the lines at once and tell Revit to create walls from these simulaneously? Or, can somebody perhaps direct me to a site where this has been discussed or figured out!!? Or even a better method than the one I described!!?

THANKS GUYS!!!!