Ben jij het ermee eens dat we eerst samen oefenen en daarna pas bespreken wat moeilijk is?

Because this is a yes/no question.

In Dutch, a normal statement would be:

Jij bent het ermee eens dat ...
= You agree that ...

But in a yes/no question, the finite verb comes first:

Ben jij het ermee eens dat ... ?
= Do you agree that ... ?

So this is standard Dutch question word order.

Yes, you could also say:

Ben je het ermee eens dat ... ?

That is very natural and often a little more neutral in everyday speech.

Using jij can add a bit more emphasis, as if the speaker is specifically asking you for your opinion. It does not drastically change the meaning, but it can sound slightly more pointed or contrastive depending on context.

It is a very common Dutch expression meaning to agree.

The full pattern is:

• het met iemand eens zijn = to agree with someone
• het ergens mee eens zijn = to agree with something
• het ermee eens zijn dat ... = to agree that ...

So in this sentence:

Ben jij het ermee eens dat ... ?
means
Do you agree that ... ?

It is best learned as a set phrase.

Because Dutch normally includes het in this idiom.

English just says I agree, but Dutch usually says:

Ik ben het eens ...
or more commonly with a reference: Ik ben het ermee eens ...

So het does not translate neatly word-for-word here. It is part of the fixed expression.

A native English speaker often wants to leave it out, but in standard Dutch you normally keep it.

Ermee is made from:

• er
• mee (from met)

This is a pronominal adverb, which Dutch uses very often.

Instead of something like met dat or met het for things or ideas, Dutch usually uses ermee, daarmee, hiermee, etc.

So ermee eens literally means something like in agreement with it/with that.

In this sentence, ermee refers to the idea expressed in the dat-clause:

dat we eerst samen oefenen en daarna pas bespreken wat moeilijk is

Yes, eens often means once, but not in this expression.

In het ermee eens zijn, eens means in agreement.

So:

• eens can mean once
• but in this fixed phrase it means agreeing

This is idiomatic Dutch, so it is best not to translate eens separately here.

A useful opposite is:

oneens zijn = to disagree

For example:

Ik ben het ermee oneens.
= I disagree with it / I do not agree.

No. They look like infinitives, but here they are actually finite present-tense verbs.

That is because the subject is we, and in Dutch the we-form of the present tense is usually identical to the infinitive:

• wij oefenen
• wij bespreken

So in this sentence:

dat we eerst samen oefenen
and
(dat we) daarna pas bespreken ...

both oefenen and bespreken are conjugated verbs, not infinitives.

A good test is to switch to a singular subject:

• dat hij eerst samen oefent
• en daarna pas bespreekt ...

That makes it easier to see that these are finite verbs.

Because after dat, Dutch usually uses subordinate clause word order.

That means the conjugated verb tends to come later in the clause:

dat we eerst samen oefenen

Here:

• dat = that
• we = subject
• eerst samen = adverbials
• oefenen = verb, placed late

The second part is coordinated with en:

en daarna pas bespreken wat moeilijk is

The subject we is understood there and does not need to be repeated.

So the structure is basically:

dat we eerst samen oefenen
en (dat we) daarna pas bespreken wat moeilijk is

Here pas means something like only then or not until then.

So:

• daarna = afterwards / after that
• daarna pas = only afterwards / only after that

It adds emphasis to the sequence:

1. first practice together
2. only after that discuss what is difficult

Without pas, the sentence would still make sense, but it would lose that extra sense of not before then.

Because this is an embedded question/embedded clause, not a direct question.

Direct question:

Wat is moeilijk?
= What is difficult?

Embedded after another verb:

... bespreken wat moeilijk is
= ... discuss what is difficult

In embedded clauses, Dutch normally puts the finite verb later, so is comes at the end.

This is very similar to English:

• direct: What is difficult?
• embedded: We discuss what is difficult.

Sometimes, but not with exactly the same feel.

In this sentence, ermee is the most standard and idiomatic choice:

Ben jij het ermee eens dat ... ?

Daarmee usually points more clearly to something already mentioned or something the speaker is mentally pointing at:

Ben jij het daarmee eens?
= Do you agree with that?

So:

• ermee is very natural in the pattern het ermee eens zijn dat ...
• daarmee sounds more explicitly tied to a specific previously mentioned idea

In other words, ermee is the safer choice for learners in this sentence.