I use the tubing as a support for the end of the staysail boom. Also if you had dorades where those 2 round vents are it would protect them from the boom (that was originally standard).
As for the box, I have never found a use for it. I thought of stashing a winch handle there so it would be handy for the 10,000 th time I went forward and forgot to take one with me, but it is neither secure, nor sun proof, nor weather proof or big enough to hold much. Maybe hold the sail ties there whilst sailing.