Is it correct to say: "Kiuj el vi volas partopreni en la komitato?" ?
The way I read the PIV entry, it's absolutely fine. (Possibly even preferable - though the entry says "transitive or with en", all the active voice examples use en.)
Is this Esperanto sentence correct? It looks like it should read "en la komitato?"
PIV says that the verb can also take an event as a direct object, without a preposition... but most of the citations include "en" so I think that's probably the more common construction.
Why "el" instead of "da" or "de"? Doesn't el mean from? So this would be "Which from you want to participate the meeting?"
It can also mean "among". That's how it's used here.
Would "kiuj de vi" work as well?
I don't think so, because el means out of (a group or series, things like that). So this is talking about out of a group