{OT} BFG Constuction help?

Today, I recieved my first three plastic Imperial BFG ships, thanks to a
judicious use of Bartertown. Everything is there, the price was right, and the
ships look pretty darn good, with extra bits and all. However...I didn't get
any instructions with these guys, and there's a few things that I can't quite
figure out. On the gun sprue, there are four short little things (about half
the size of the antenna mounted atop the ship) that look like guns. What are
these, and where do they go? And what fits into the square holes on the
underside of the ships' "wings"?

To avoid boring the list as a whole to death, please e-mail me directly.
Thanks for the help, all.

Now I just have to figure out how to paint them....