"Are you going to Kyiv now?"
Translation:Ви їдете у Київ зараз?
"Ідете" is correct but it means going by foot and sounds weird in this particular case. Something archaic, as if someone goes to a city by foot like in olden times.
It is accusative and not locative, because it indicates a movement to a place and not a location of an action.
So let me get this straight : іти and їхати mean going somewhere just one-way, yes? And ходити and їздити are used for round trips or habitual movement? So if that is correct, then ходити and їздити can never be used in the present tense, right? You can't say you are going somewhere right now habitually. And you can't say you are presently going somewhere and coming back (because in this present moment you're in the course of going, and therefore the coming back part wouldn't happen till later in the future). Does any of that make sense?
You can't say you are going somewhere right now habitually.
Right, but you can say "you go somewhere on a regular basis." For example, "My daughter goes to school every day" - "Моя донька ходить в школу кожного дня."
Okay, so you are required to use phrase like "every day" or "weekly," in order to use ходити in present tense ? You couldn't just say "моя донька ходить в школу" on its own, right?
No, you are not required to use those phrases. I used them to emphasise that the action is habitual.
Ви їдете зараз у Київ? Ви зараз їдете у Київ? - абсолютно корректні і українською звучать краще, ніж "Ви їдете у Київ зараз?"