HOW to use opengl and is my grid ok for large scene using imperial

I was wondering how to do this and if my settings are ok or if anything needs to be changed in user preferences under system? does opengl work in cycles? and for world sky, do I change anything? also, if I use imperial for real world scale. to change my grid for a large scene do I just increase the lines but leave scale alone? file should show what I have

I think this looks good

http://www.pasteall.org/blend/34784