1. We tried to improve some of that. I'm not sure there is an easy way for us to detect expiry but please file an RFE and we'll try to check that
2. It's something we added a few months ago and it should work. Is your plugin up to date? Which IDE are you using and what exactly did you see?
I'm assuming you used the version in Codename One Settings?
3. That's Codename One Settings. It always offers to update the build.xml if there is a change. We probably need to do something similar to what netbeans did and move all of our code into an impl.xml. That's something we are thinking about as part of an overhaul of Codename One's update process which needs more work.