In order to mutually ask and answer questions Jochen suggests to just meet at the matrix.org #facturx room the next three Thursdays (19.12., 26.12. and 02.01.) between 16:00 and 17:00 CET.
This chat “room” already exists and is open 24h/day at https://app.element.io/#/room/#facturx:matrix.org and you can already ask questions now. Matrix may require an account but you can use whatever client you want and of course it is for free and you dont need additional credentials to join the public #facturx room.
Of course you are free to ask anybody any question (e.g. RE Quba, Factur-X, XRechnung, B2B e-invocing) at any time but if you are totally new to the topic it would be appreciated if you previously had a chance to familiarize with the topic by e.g. having a look at https://medium.com/@jochen.staerk/why-and-how-germany-bans-b2b-paper-invoices-a4c7977f314a and/or try the (german domestic B2B) samples at https://github.com/ZUGFeRD/corpus/tree/master/XML-Rechnung/ .
So see you there, if you like 🙂