and sometimes trains may be stacked on the same platform - at times your train may not be the one right by the entrance to the platform but one half way up - not common but have seen it, especially in large stations.

Look on the outside of the train cars to be sure where that specific train is headed!

If buying those deep discounted tickets on www.bahn.de/en then it is imperative to book in ample time to transfer as though if trains are late you may be able to re-book or use them on another train if not and you miss your train you ticket I believe become null and void and you then have to buy the full-fare ticket you wanted to avoid in the first place.

If traveling more than a few times on inter region trains then look at the Germany Railpass (Twin if two traveling together).

Thanks to all for your advice. We have a twin railpass so we won't be locked into specific trains. Hopefully we won't have any issues.