How to set a Random Rotation? / Reflection

Nodebox beginner, here:

I have svg shapes representing tiles in an overlapping grid-based array.
The tiles can be oriented up to 8 different ways:
• Rotation Angle: 0, 90, 180, 270 (which I've figured out how to generate from Angle and Range Nodes)
• Side: Front or Back (basically a boolean)

But I can't figure out how to randomly pick from the 4 possible angles and 2 sides.
I've tried Shuffle->First1 but the shuffle result is always constant unless I vary the seed manually which defeats the point of a random output.

How do I randomly select 1 from my ranges?

Much appreciated,
Dimitry

Here is test image for where I'm stuck--all arrows have same orientation instead of what is desired (above).

I think it might be a problem of where you put the shuffle/rotate node -
e.g. at the 'top' of a 'chain', it will only influence the source geometry (all arrows will have the same orientation), while at the 'bottom', it can influence every arrow in the grid -
well, that is a bit hard to explain :P

But I came up with an example, see the attached screenshot & .nbx