In answer to the question on whether nUI has the ability to customize the action bars orientation and size the answer is yes but in version 5 it involves editing a layout file and using the mover system to move the frames around and will take some trial and error to get it to your preference.
Someone a long ways back did make a layout change for the action bars for the special N52 or whatever it was called keyboard.
Ah here it is..
http://www.wowinterface.com/forums/s...70&postcount=6
Take a look at that and at the screenshot he attaches. Hopefully it will give you hope that something is possible.
Version 6 is supposed to be more user configurable without file editing or so Scott says so that will hopefully make things easier.
Bear in mind though that any change you make to the nUI folder will get overwritten when you patch up to a later version so you will have to make sure you keep a copy to reintegrate into the newer version.