"Who drinks juice with ice?"
Translation:Kiu trinkas sukon kun glacio?
Kinda, whom can also be used with prepositions, as in "On whom do you plan to rely?"; the -n in esperanto is only used with (1) verb objects or (2) parts of the sentence indicating the direction of some movement, as in "La birdo flugis en la ĝardenon". See uses (1) and (2) http://vortaro.net/#-n
Also keep in mind, kiu(n) can also be a thing other than a person, as long as it's not generic but specific/known.
el tiuj libroj kiun vi prenos? Of those books, which will you take?
Hope this is clear enough, I'm a beginner myself and English isn't my mothertongue :-)