Wij kiezen de achttiende kamer.

Yes. Wij and we both mean we.

• wij is the stressed/full form
• we is the unstressed/common spoken form

So:

• Wij kiezen de achttiende kamer.
• We kiezen de achttiende kamer.

Both are correct. Wij can sound a bit more emphatic or careful, while we is very common in everyday speech.

Because the subject is wij (we), and the verb has to agree with it.

The verb is kiezen = to choose. Its present tense forms are:

• ik kies = I choose
• jij/je kiest = you choose
• hij/zij/het kiest = he/she/it chooses
• wij/we kiezen = we choose
• jullie kiezen = you all choose
• zij/ze kiezen = they choose

So with wij, you use kiezen.

The sentence follows the normal Dutch main-clause order:

subject + verb + object

So here:

• Wij = subject
• kiezen = verb
• de achttiende kamer = object

This is very similar to English We choose the eighteenth room.

Because in Dutch, singular countable nouns usually need an article or another determiner.

So you normally say:

• de kamer = the room
• een kamer = a room
• de achttiende kamer = the eighteenth room
• onze kamer = our room

Using just achttiende kamer by itself would sound incomplete in a normal sentence.

Achttiende means eighteenth. It is an ordinal number.

It comes from:

• achttien = eighteen
• achttiende = eighteenth

Dutch ordinals are often made by adding -de or -ste:

• vier → vierde = fourth
• tien → tiende = tenth
• achtien/achttien → achttiende = eighteenth
• twintig → twintigste = twentieth

So achttiende is the ordinal form used before a noun.

Because it is being used like an adjective before a noun, and in this sentence it takes the usual -e ending.

In Dutch, adjectives before nouns often get -e, especially after de words.

Here:

• de kamer
• de achttiende kamer

This same pattern appears in many phrases:

• de grote kamer = the big room
• de eerste kamer = the first room
• de achttiende kamer = the eighteenth room

So the -e ending is normal here.

Because kamer is a de-word in Dutch.

Dutch nouns are grouped as either:

• de-words
• het-words

kamer belongs to the de group, so you say:

• de kamer
• de achttiende kamer

You have to learn the article together with the noun:

• de kamer = the room

It is an ordinal number, but in the sentence it behaves grammatically a lot like an adjective because it comes before the noun and describes which one.

Compare:

• de grote kamer = the big room
• de achttiende kamer = the eighteenth room

So it is still a number, but it functions in the noun phrase in an adjective-like way.

Yes, that is possible, but it sounds more marked or emphatic.

Normal neutral order is:

• Wij kiezen de achttiende kamer.

If you move something else to the front, Dutch still keeps the finite verb in second position:

• De achttiende kamer kiezen wij.

That version puts extra focus on de achttiende kamer.

Learners often find this word tricky because of the consonants.

A rough guide is:

• achttien ≈ AKH-teen
• achttiende ≈ AKH-teen-duh

Notes:

• The ch in acht is the guttural Dutch sound, not like English ch in chair
• The ending -de is usually a soft duh sound
• The ie in tiende sounds like ee

You do not pronounce every written consonant as strongly as an English speaker might expect.

Yes. In Dutch main clauses, the finite verb is usually in second position, so if another element comes first, the subject can move after the verb.

Compare:

• Wij kiezen de achttiende kamer.
• Vandaag kiezen wij de achttiende kamer. = Today we choose the eighteenth room.

So wij comes first in your sentence because nothing else is placed before the verb.