I seldom need to show people whispering or talking in a low voice, and I've tried a few different methods of showing it in the past. I think the simple smaller font size works well enough.

Oh and yes, Professor Jones is ordering a last meal in the first panel. Naturally he speaks German fluently. He's ordering pork knuckle with Swabian/Bavarian noodle/dumpling thingies (spätzle are kind of hard to describe succinctly), potato salad "with those little bacon bits", and black forest cake and apple strudel for dessert.

Mmmmm...