1 :( harlequins. Agony. I spent several minutes remembering the name paggliaci and had it written in there until after I assigned D, then decided it was (a) a single guy's name and (b) a lot of syllables for a profession aimed at children. I knew harlequin was a character from Italian theatre so went with that.
2 :( wingback. I don't know what a wingback chair is, but I assumed there was some aviation connection because of SAS.
3 :( Underground Railroad. I figured it was something to do with civil war. I don't know if pony express fits that bill.
4 :( Hawkeye. Was hoping for some sort of mash spin off.
5 :) Michael Jackson. I knew MJ died in 2009 and thought there was a musical about him (I think Alex Nolan was involved)
6 :) helium. Wasn't sure how to separate helium and argon but went helium because it had such a low atomic number that I could imagine it had the more extreme properties.