Language: with the exception of Julie D'Aubigny, everyone speaks German, luckily for me. ;) Everyone also speaks French and English. Latin: Humboldt, Rahel Straus and Boswell, definitely; not sure about Tesla, but most likely. Hedy Lamarr and Julie D'Aubigny, no. (Ancient) Greek: Humboldt yes, Rahel maybe (can't remember whether that was a must for medical studies at the time, but it may very well have been), Tesla as a Serbian with an Orthodox priest as an uncle maybe enough for religious services, everyone else no; Rahel also speaks Hebrew, and I assume Tesla might have some command of the most popular languages in the Austro-Hungarian Empire in addition to German (and Croatian). Which means no Ancient Egypt and the likes for us (unless we're talking Ptolemaic period), if we don't have an equivalent to the Universal Translator on board. If we don't, Tolkien would be indeed an inspired choice!