kanji don't really "stand for" sounds, though they have (several) associated readings, or sounds that they represent depending on context
hiragana and katakana are known as syllabaries, not alphabets. characters are known as phonemes, not letters. so, yes. you can't make a "k" sound in Japanese; you can only say ka/ki/ku/ke/ko. "n" is the only standalone consonant, and it can only appear after a vowel (kan is okay, but you have to say na as a syllable, you can't concatenate n+a)
I know what "aucun" means but unfortunately the context that it's being used in here doesn't have a subject--it's just aucun/aucune by itself, without homme/femme or any other subject stated explicitly. so it's having to take an implied gender. and I'm having to think of a one word aucun translation, which, as you rightly pointed out, doesn't make much sense.
thanks, tho!