Thanks for these code patches! I was worried that I wouldn't be able to continue using Shopadmin after updating to 1.5.5, but now it is up and running. I really appreciate the contributions in this thread.

Has someone put together a .zip package with all the 1.5.5 patches applied so that others can have a simpler fix? I would upload it but I don't want to claim credit for any of the code changes.