2. How are updates authenticated? I'm aware, each object has a "mntner" but how and where is the Maintainer identity part of request to the API?
Authentication is done via the maintainer's password.
3. the Test-DB did not contain any objects related to our company - that's OK. But could I add them? And how? I guess I may use 'https://apps-test.db.ripe.net/search/lookup.html?source=test&key=TEST-NCC-HM-MNT&type=mntner' Right?
There is the test database maintainer (TEST-DBM-MNT) you can use to set up everything using the password "emptypassword". once you have your own maintainer set up, use that one. see also https://github.com/RIPE-NCC/whois/wiki/WHOIS%20REST%20API%20Migration%20Guid... Regards, Alexander Stranzky -- velia.net Internetdienste GmbH * Hessen-Homburg-Platz 1 * D-63452 Hanau Geschäftsführer: Franz G. Köhler, Arek Akilli * AG Hanau * HRB 7588 Tel: +49 6181 1898119 * http://www.velia.net Follow us on twitter: https://twitter.com/velia_net