Hi Graham,
The build you are seeing is the build from immediately before the beta release. It contains the same code and files as the 1.0.0-beta1 release.
We use a build with the alpha+migration version number here so that the site will receive the upgrade to the latest beta release immediately after migration. We’re looking at a couple of options to make this work more smoothly, but there are some challenges. Among them: the version of ClassicPress used by the migration plugin needs to be a separate build with a different file structure.
As for your other questions, I will reply here shortly, but generally it is better to create a new forum topic for each separate issue or question.