Hey guys! I just jumped in and read only the last page so far. Weeeeell.
On german trains you mostly have "Warsteiner", which is a Pilsener (or "Pils" in short). Warsteiner is pretty much okay with most people, while there's always a discussion if the big beer breweries do make good beer after all. In general, no one denies a Pils on a train anyway.
Be careful if you get into a train calles "Metronom". There are several trains of local railway societies in which you are not allowed to drink alcohol.
Well, if you're looking for help or a little chat, most of the metal looking folks will love to have a little chat in English, whether they can actually speak the language or not. I think this has changed over the past 10 to 15 years, there're a lot more people who like speaking in foreign languages they know. This was much worse a decade ago.
No need for beer here, a smile will do it.
Could be that some fucking youngsters in their hip clothes or gangster rapper outfit or some other poser shit will not give a fuck, but hey, we know that kind of lads, right?