"I would like you to work on some Arithmancy and also some Ancient Ruins." Stonehenge and Malmsbury Abbey perchance? I don't think they'd fit in the classroom. The word you were looking for is RUNES.
“I’m Capitan you know!” Yes, Herr kapitan, ve vill vin ze house cup zis year.
"You know it’s really ingratiating not knowing how many of these ‘spottings’ are real." I suppose the fact that Harry had been "spotted" could try and charm it's way into being liked, but I doubt it.
"you’ll come to the old Charmed classroom." Charmed, I'm sure.