Here some answers:
1. The report RDA_MAINTAIN actually comes with the Add-On installation, yes.
2. Actually the creation of a secondary DB connection is independet from the Add-On installation. Once you want to use the Add-On, you need to have it to be able to switch. This is done by defining scenarios and activating them. In the scenario you also have to enter the secondary DB connection which has to exist before.
3. You don't have to use a Z-report. I tried it, too, and I found it not so difficult to work with an XML file. But it is great to use the Z report to show the content of a scenario.
Best regards,
Michael