Я хочу заранее выяснить, во сколько начинается встреча и кто ещё придёт.

Because everything after выяснить is what the speaker wants to find out:

• во сколько начинается встреча
• кто ещё придёт

These are two indirect questions, both depending on выяснить. In Russian, a subordinate clause like this is normally separated by a comma.

There is no comma before и, because the two indirect questions are treated as parallel parts of the same structure:

• выяснить, во сколько... и кто...

So the punctuation is:

• comma before the whole subordinate part
• no extra comma between the two linked questions

Заранее means in advance / beforehand.

Here it modifies выяснить:

• хочу заранее выяснить = want to find out beforehand

Its position is flexible, but хочу заранее выяснить sounds very natural. You could also say:

• Я заранее хочу выяснить...
• Я хочу выяснить заранее...

But the original version is probably the most neutral and smooth.

Both can often be translated as to find out, but they are not always identical.

• выяснить often suggests clarifying or establishing something clearly
• узнать often means to learn / to come to know

In this sentence, выяснить fits well because the speaker wants to sort out specific details:

• what time the meeting starts
• who will come

So выяснить gives a sense of checking and clarifying information.

Also, выяснить is perfective, which matches the idea of a completed result: to get the information.

Во сколько asks specifically about the clock time:

• Во сколько начинается встреча? = What time does the meeting start?

Когда is broader:

• Когда начинается встреча? can mean When does the meeting start?, but it could invite an answer like tomorrow morning, on Monday, or after lunch, not necessarily an exact time.

So if you want a specific time such as at 3:30, во сколько is the natural choice.

Russian normally uses the set expression во сколько when asking about time.

For example:

• Во сколько ты придёшь?
• Во сколько начинается фильм?

The form во instead of в is used here for pronunciation and is simply the standard idiomatic form. Learners should usually memorize во сколько as a fixed phrase meaning at what time.

This is very common in Russian. The present tense of an imperfective verb is often used for:

• schedules
• timetables
• planned events

So:

• Во сколько начинается встреча?

literally looks like At what time does the meeting begin?, but it often refers to a future scheduled event:

• What time does the meeting start?

English does something similar:

• What time does the train leave tomorrow?

So this is not strange Russian grammar; it is a normal way to talk about scheduled future events.

Both are possible in some contexts, but they are not used in exactly the same way.

• начинается = imperfective, often used for scheduled or regular events
• начнётся = perfective future, focuses more on the single future start itself

In a question about the official start time of an event, Russian often prefers:

• Во сколько начинается встреча?

This sounds very natural for a meeting, class, film, conference, etc.

Во сколько начнётся встреча? is also understandable and can sound fine, but начинается is especially common when asking about a scheduled event.

Because встреча is the subject of начинается.

The clause is:

• во сколько начинается встреча

Literally:

• at what time begins the meeting

Here, встреча is the thing that begins, so it stays in the nominative:

• встреча

Both are possible.

The shorter version:

• кто ещё придёт

works because the meeting has already been mentioned, so на встречу is understood from context.

If you want to be more explicit, you can say:

• кто ещё придёт на встречу

Russian often leaves out information that is already obvious from the context.

Here ещё means else / in addition / besides.

So:

• кто ещё придёт = who else will come

This is a very common use:

• Что ещё нужно? = What else is needed?
• Кто ещё там был? = Who else was there?

Be careful: ещё can also mean still in other contexts, so its meaning depends on the sentence.

Придёт is the future form of the perfective verb прийти (to come / to arrive).

It is used because the speaker is asking about a future completed action:

• who will come / arrive

Russian perfective verbs do not have a present-tense meaning like English present tense. Their so-called present forms actually refer to the future:

• приду, придёшь, придёт...

So:

• кто ещё придёт = who else will come

Кто ещё придёт is the normal neutral order.

Russian word order is flexible, but it is not random. Here:

• кто introduces the indirect question
• ещё naturally follows it
• придёт comes at the end

So the standard pattern is:

• кто ещё придёт

A different order like ещё кто придёт would sound marked, unusual, or context-dependent.

Yes, that is close to the structure of the Russian sentence, and it can help you understand the grammar.

A more natural breakdown is:

• Я хочу = I want
• заранее выяснить = to find out beforehand / in advance
• во сколько начинается встреча = what time the meeting starts
• и кто ещё придёт = and who else will come

So the Russian structure is very logical: I want to find out in advance [what time the meeting starts] and [who else will come].

Here it is followed by indirect-question clauses, not by more infinitives.

Compare:

• Я хочу выяснить, где он живёт.
• Я хочу выяснить, почему она ушла.
• Я хочу выяснить, кто придёт.

After выяснить, Russian often uses clauses introduced by question words like:

• где
• когда
• почему
• кто
• во сколько

So in this sentence, the speaker wants to find out two pieces of information, each expressed as a clause.