With RE's help, got four new exists deployed, with their apps working, and publicly available. Lesson learned:

• For configuration and deployment of the XAR, use Chrome, and connect to the internal :8080 address. If you connect through Apache, you risk a timeout during deployment, which will bork eXist completely.

Other than one case of that happening with the MoEML app, everything worked as planned; the deployment script goes seamlessly, the XARs all worked, and everything looks good. Couple of bugs to fix in MoEML and Mariage.