Wow! I have this kit that I bought a very long time ago and have recently just started working on again! Which brought me here, so thanks for posting all of this great info!
I'm guessing my kit is the older. It looks like its from 2001 and is depicting the 100th sts with Endeavour. It explains the cargo included which is the same in the kit you have. It says Endeavour visited the ISS. It carried a robotic arm which was installed on the ISS. I am not sure if the pay loaded pices included are part of the mission or not, but it describes these pieces as well. There is a space lab for one half. The other section is an ESA experiment module with a telescope mounted to it. It also contains the experimental arm.
I wish I had your decal kit for sure. There are hardly any decals for thethe cockpit. The escape door on the side didn't match any of the pictures of the shuttle I found, which led me to painting almost all details on it by hand. There were no decals for the edge of the wings. I ended up taping these lines off to paint them in.
I would like to try and add something to the cargo bay to make it look padded. I would also like any suggestions as how to make the exterior look weathered. I don't really have any ideas on these things yet. For anyone interested, I can try to post photos of what I have done so far!