OpenGL Viewports

I'm writign a 3D pool game, and want to have a plan view of the table aswell as the main 3D view

is it possable to only draw the scene once and have 2 separate viewports with different camera settings or will I have to draw it for each viewport?

in pseudocode

Code:

create viewport
setup camera

create second viewport
set up second camera

draw pool table

or

Code:

create viewport
setup camera
draw pool table

create second viewport
set up second camera

draw pool table

the only difference is that I draw the table trice on the second one, and I dont think it will effect performance too much, but if it can be drawn once it would be more convenient and give a small increase in performance

another question
when opening a window to draw to how do you make sure that the editable area of the window is at for example 640x480 and the window border goes around that?

Create two camera's, Capture the scene, Convert the captured
2 scenes to textures, Scale the textures to 1\2 the screen on the
y axis, Render the textures in the orthographic mode.