Questa questione ci importa molto.

Because questione is a feminine singular noun, so the demonstrative has to match it.

• questa questione = this issue / this matter
• questo problema = this problem

In Italian, words like this change form depending on the gender and number of the noun:

• questo = masculine singular
• questa = feminine singular
• questi = masculine plural
• queste = feminine plural

Questione usually means issue, matter, or question in the sense of a topic under discussion.

So in this sentence, it does not mean a direct question like What time is it? In that sense, Italian usually uses domanda.

Compare:

• una domanda = a question someone asks
• una questione = an issue, matter, topic, or dispute

So Questa questione is more like This issue or This matter.

Here, ci means to us.

So:

• ci importa = it matters to us

This is an indirect object pronoun. Other forms are:

• mi importa = it matters to me
• ti importa = it matters to you
• gli importa = it matters to him
• le importa = it matters to her
• ci importa = it matters to us
• vi importa = it matters to you all
• gli importa = it matters to them

In this sentence, ci tells you who is affected: us.

Because questa questione is the subject, and ci is not the subject.

Italian importare in this meaning works like to matter or to be important to someone.

So the structure is:

• Questa questione = the thing that matters
• ci = to us
• importa = matters

Literally, the sentence is structured like:

• This issue matters to us a lot.

Since questione is singular, the verb is singular: importa.

If the subject were plural, you would use importano:

• Queste questioni ci importano molto. = These issues matter to us a lot.

It can be, but not here.

Italian importare has more than one meaning:

• importare merci = to import goods
• importare a qualcuno = to matter to someone / to be important to someone

In your sentence, it clearly means to matter.

This is a very common thing in Italian: one verb can have different meanings depending on how it is used.

Because that would mean something completely different.

• Noi importiamo questa questione would sound like We import this issue, which makes no sense in normal usage.
• To say This issue matters to us, Italian uses the pattern [thing] + indirect object + importa.

So Italian does not express this idea as we matter this issue or we care this issue. It uses a structure closer to:

• This issue is important to us
• This issue matters to us

Yes. That is a very natural alternative.

• Questa questione ci importa molto.
• Questa questione è molto importante per noi.

Both are correct, but they are not exactly identical in feel.

Ci importa molto often sounds a bit more personal or emotional, like:

• we really care about it
• it matters a lot to us

È molto importante per noi is slightly more neutral and descriptive:

• it is very important for us / to us

So both work, but ci importa molto can feel a bit more engaged.

Because molto is modifying the verb phrase ci importa and means a lot / very much.

So:

• ci importa molto = it matters to us a lot

Putting molto at the end is very normal in Italian.

You may also hear slightly different word orders for emphasis, such as:

• Questa questione molto ci importa — possible, but not the normal neutral order
• A noi questa questione importa molto — emphasizes to us

The basic neutral sentence is exactly the one you have.

Yes.

You can say:

• Questa questione importa molto a noi.

But in normal Italian, using the pronoun ci is usually more natural:

• Questa questione ci importa molto.

You can also combine them for emphasis:

• Questa questione a noi ci importa molto.

That sounds emphatic, as if you are stressing to us in particular. In careful grammar teaching, this doubling may be discussed as redundant, but in real Italian it is common for emphasis.

A cleaner emphatic version is:

• A noi questa questione importa molto.

Yes, although depending on context, Italians may also use other expressions.

Common possibilities include:

• Mi importa. = It matters to me.
• Non mi importa. = I don’t care. / It doesn’t matter to me.
• Ci tengo. = I care about it.
• È importante per me. = It’s important to me.

So importare in this sense is absolutely standard and useful. In fact, Non mi importa is a very common everyday phrase.

The verb would change to agree with the plural subject.

Singular:

• Questa questione ci importa molto.

Plural:

• Queste questioni ci importano molto.

Notice the changes:

• questa → queste
• questione → questioni
• importa → importano

The pronoun ci stays the same because to us does not change.

Yes:

• Ci importa molto questa questione.

That is grammatically correct. It puts a little more focus on the fact that it matters to us.

Compare:

• Questa questione ci importa molto. = neutral, topic-first
• Ci importa molto questa questione. = slightly more focus on matters to us

Italian word order is more flexible than English, but the original version is a very natural standard order.

Yes. English often uses care about, but Italian does not translate it word-for-word in this structure.

A learner might want to say something like:

• Noi curiamo questa questione or something similar

But that would be wrong for this meaning.

Instead, Italian uses expressions like:

• Questa questione ci importa molto.
• Ci teniamo molto a questa questione.
• Per noi questa questione è molto importante.

So when English says We care a lot about this issue, Italian often prefers a structure like:

• This issue matters a lot to us rather than trying to copy the English grammar exactly.