you can read one. but there are more, try using search tab.
Can you point me to any of the posts you mention? To clarify, what is coming on the com port is the layer 2 frame as is right?
What you can see is the frame as is, with headers and all fields.
Also the libelium catalog says one can use the gateway to send "commands" to the WSN. What does this mean?
What do you mean? sending at commands to Xbee modules? or sending information to other Waspmotes?
Do I have to prepare the entire 802.15.4 frame without the aid of the 802.15.4 api used on the motes and send that to the com port? How does that work?
Yes, but there are many ways to do it, using Java or other methods.
Maybe Digi's documentation available on Digi's website
is also useful for you.
Let us know your comments.