"Where do we start?"
Translation:Kie ni komencas?
"komenci" is not a verb of motion. So there's also no direction and thus no accusative of direction.
-ien correlatives mark motion, while -ie correlatives mark location. Other correlatives (e.g. kio) still take the accusative when they would normally take the accusative. http://donh.best.vwh.net/Esperanto/correlatives.html
That website has always put a bad taste in my mouth and unfortunately they are too many Esperanto speakers with the same attitude.
"The correlatives are the bete noir of many English-speaking students of Esperanto; they never seem to get them right. This is, in my opinion, a simple lack of diligence on their part; even memorizing the fifty words separately should take no more than the better part of an evening. "
In other words, if you get them mixed up or wrong you are an idiot.
Not quite. It's not due to correlative or noun, it's due to the function of the correlative in the sentence.
Well... If we were classes wanting to start in a school, we would say that :D But normally we only start something (we start eating, we start sleeping, we start making, we start going...). "Komencigxi" is for the other meaning of "start" (the TV show started, a new age starts...)
Are pronouns absolutely necessary? If in context, one were to say "kie komencas?" Would they be understood? Would it be strange?