How to merge two faces by creating a third I'm very new at blender and sometimes I get stuck in stupid problems, but I want to know how to merge two faces by creating a third as a "bridge".

Here's a pic where I'm stuck 

I want to merge these two selected edges by creating a face with the same dimensions of the one at bottom.

Here's what I want

is it possible to do this without knowing the exact dimensions of the face at bottom? if not, how do I get the properties such as Dimension/Position/Angle of the selected face??

Thanks in Advance
Here is a two-step solution:

1) Duplicate your face
Mesh->Duplicate
Shortcut: Shift+D  



...and move it up
- use snapping options
- use orthographic view and side view to be more precise  



2) Select your edges and connect them with a new face.
Vertex->New Face
Shortcut: F