15 letters Where to look for hidden words in this puzzle's fifth and eleventh columns? Answer: BETWEENTHELINES
15 letters He said "In America, anybody can be president; that's one of the risks you take" Answer: ADLAIESTEVENSON
15 letters Ominous request from a teacher ... or a hint to the first words (and following letters!) of 17-, 26- and 43-Across Answer: SEEMEAFTERCLASS
15 letters Who quipped "God tells me how the music should sound, but you stand in the way" Answer: ARTUROTOSCANINI