I downloaded the RC2 build from Blender.org, and have been using it on a project. Some of the things I am seeing:
Array modifier - Relative Z offset doesn’t work. X and Y do, but I had to use Constant Z to make it move in Z axis
I could not flip normals. Well at least with draw normals on, the direction did not flip. They did re-orient correctly when using ctrl-n - recaculate outside.
After a while, the buttons would not show in the buttons window. I normally work in 4 viewports and 1 buttons window. I had to change one of the windows I typically use for 3D into a buttons window.
This is the expected behaviour. The offset is relative to the size of the object over that axis, so that for offset 1, the object is placed right after the previous object. With size 0 over the z-axis, the plane isn’t supposed to move.
OK, but why does it move with constant offset? - OK, I think I understand. In my test, I tabbed into edit, selected all verts, and rotated - this bought the relative Z offset into play.
Yes, the constant offset is basically using global coordinates, but the relative offset is using the actuall size of the object. if the object is five units in all directions, having the relative offset at one will make them all five unit appart, but constant offset will make them one unit appart.
i don’t know what’s wrong with your buttons. Try updating your graphics card drivers.