A thought on the yellow goal posts:
Most if not all NFL teams have yellow posts, as do many colleges. I do not believe any rule exists.....but I did a simple search on Google for "Conference USA football stadiums" and from the images I found, every single team in C-USA has yellow posts. Coincidence? Or it could be that yellow is just cheaper, idk
edit: Another thought struck me; it could be that the white posts would blend into the field lines on T.V. Yellow gives T.V. viewers a distinct image of the goal posts vs. white posts on white lines. This is all conjecture, haha