How do I map buttons on my joystick? I have 12 and this game only seems to use 2. The way I see it I should be able to do everything but chat with one (including launch/land, turn on/of a/f mode, target closest, cycle targets, navigate menus, etc...).

Is there a trick to this I missed?

Press F1 while ingame. Go to input: keyboard & joystick. There you can assign your joystick buttons to specific functions by selecting function and pressing the key on your joystick you want to perform said function.
Save and exit.

you can also manually edit the wgaf file and assign anything you want including the "push to talk" there is a listing of all the commands in the manual under app_commands.html.

If you are editing wgaf directly note that the button numbers recognised by vo may be 1 less than marked on the JS itself .