Ha mindenki kész, továbbindulunk.

Because Hungarian normally omits the verb van (is) in the present tense, 3rd person when the predicate is a noun or adjective.

So:

• Mindenki kész. = Everyone is ready.
• literally: everyone ready

But in other tenses, or in 1st/2nd person, the copula appears:

• Kész volt. = He/she was ready.
• Készek lesznek. = They will be ready.
• Kész vagyok. = I am ready.

So this sentence is completely normal without any separate word for is.

Because mindenki means everyone/everybody, and in Hungarian it behaves grammatically as singular.

That is why you get:

• Mindenki kész.
• Mindenki eljött. = Everyone came.

Not plural agreement.

This is similar to English in some ways: everyone is ready, not everyone are ready.

Grammatically, ha means if.

However, in sentences like this, English often prefers when or once:

• Ha mindenki kész, továbbindulunk.
• natural English: When/Once everyone is ready, we’ll move on.

So Hungarian still uses ha for a real condition whose fulfillment is expected.

If you want a more purely temporal when, Hungarian often uses amikor, but here ha is the normal choice.

It has three main parts:

• tovább = further, onward
• indul = start, set off, depart
• -unk = we

So:

• indulunk = we set off / we leave
• továbbindulunk = we move on / we set off again / we continue onward

The exact English translation depends on context, but the idea is resuming movement or continuing the journey/process.

Because tovább functions here as a verbal prefix or preverb (igekötő) attached to indul.

When the prefix stands directly before the verb, Hungarian usually writes them together:

• továbbindulunk

But when something splits them, they are written separately:

• Nem indulunk tovább. = We are not moving on.
• Mikor indulunk tovább? = When do we move on?

So the spelling changes with word order.

Because Hungarian very often uses the present tense for future meaning when the context makes the future clear.

Here the condition makes the timing obvious:

• Ha mindenki kész, továbbindulunk.

This naturally means:

• If/when everyone is ready, we’ll move on.

Hungarian can form an explicit future with fog:

• Ha mindenki kész, tovább fogunk indulni.

But that version is usually less natural here. The simple present is the normal choice.

Because Ha mindenki kész is a subordinate clause and továbbindulunk is the main clause.

Hungarian normally separates these with a comma:

• Ha mindenki kész, továbbindulunk.

If you reverse the order, you still use a comma:

• Továbbindulunk, ha mindenki kész.

So the comma is standard clause punctuation.

Yes, you could, and it is understandable and natural.

There is a small difference in feel:

• Mindenki kész = compact, simple, very common
• Mindenki készen van = more explicit, a bit fuller

Hungarian often uses both kinds of structure around kész:

• A vacsora kész. = Dinner is ready.
• A vacsora készen van. = Dinner is ready / finished.

With people, you may also hear:

• Mindenki készen áll. = Everyone is ready / standing by.

In your sentence, mindenki kész is short and perfectly idiomatic.

Yes. Hungarian word order is flexible, but different orders can change the focus or emphasis.

For example:

• Ha mindenki kész, továbbindulunk.
  Neutral: If everyone is ready, we’ll move on.

• Továbbindulunk, ha mindenki kész.
  Same basic meaning, but the main action comes first.

Hungarian word order is not random: it is strongly connected to information structure—what is being presented as the topic, focus, or contrast.

So yes, the order can change, but the original sentence is a very natural neutral version.

Because mindenki refers to people: everyone / everybody.

Compare:

• mindenki = everyone
• minden = everything / every

So:

• Mindenki kész. = Everyone is ready.
• Minden kész. = Everything is ready.

This is an important distinction in Hungarian:

• ki is connected with people
• mi / minden is connected with things

No, it does not need it.

Hungarian can say:

• Ha mindenki kész, továbbindulunk.

This already means If everyone is ready, then we’ll move on.

You can add akkor for emphasis:

• Ha mindenki kész, akkor továbbindulunk.

But in many everyday sentences, Hungarian simply leaves akkor out. The meaning is still perfectly clear.