Hvis vi skal skifte spor, spørger jeg konduktøren, hvor vi skal stige af.

Because the sentence starts with an if-clause: Hvis vi skal skifte spor.

In Danish, when a subordinate clause or another element comes first, the finite verb usually comes before the subject in the main clause. This is the normal V2 word order rule.

So:

• Jeg spørger konduktøren ... = I ask the conductor ...
• Hvis vi skal skifte spor, spørger jeg konduktøren ... = If we need to change tracks/platform, I ask the conductor ...

The first part takes the first position, so the verb spørger comes next.

Because this is an embedded question or indirect question.

Direct question:

• Hvor skal vi stige af? = Where should we get off?

Indirect question:

• Jeg spørger ..., hvor vi skal stige af. = I ask ..., where we should get off.

In indirect questions, Danish uses subordinate-clause word order, so the subject usually comes before the verb:

• hvor vi skal ...

That is why it is not hvor skal vi ... here.

The two instances of skal belong to two different clauses:

• Hvis vi skal skifte spor = if we need to change track/platform
• hvor vi skal stige af = where we should get off

So each clause has its own verb phrase, and each one happens to use skal.

In Danish, skal can mean things like:

• must
• need to
• am/is/are supposed to
• sometimes a future-like meaning depending on context

Here it is closer to need to / are supposed to.

Literally, it means change track.

In transport contexts, it can mean something like:

• changing to another track
• moving to a different platform/track
• switching trains or direction, depending on context

The exact English translation depends on the situation. Danish often uses spor where English might say track or sometimes even platform, depending on what the speaker really means.

Konduktøren means the conductor. The ending -en is the normal Danish way to make many common nouns definite.

Compare:

• en konduktør = a conductor
• konduktøren = the conductor

So here the speaker means a specific conductor, not just any conductor.

Stige af means get off or disembark.

It is a verb + particle combination, similar to English get off.

In Danish, the particle often appears at the end in infinitive constructions:

• skal stige af

Other examples:

• Jeg står af toget. = I get off the train.
• Vi skal stå af næste gang. = We have to get off next time.

So af belongs with stige, even though it stands separately.

Yes, it is common and natural in travel contexts, especially for trains, buses, and similar transport.

However, Danish also often uses stå af in everyday speech:

• Hvor skal vi stå af? = Where should we get off?

So stige af is correct and understandable, but stå af may sound a bit more everyday in some situations.

Danish often does not need an extra word like then after an if-clause.

English might say:

• If we have to change tracks, then I ask the conductor ...

But Danish very naturally says:

• Hvis vi skal skifte spor, spørger jeg ...

The meaning of then is already understood from the structure.

Because Danish often uses the present tense for actions that are habitual, planned, or understood from context.

So:

• Hvis vi skal skifte spor, spørger jeg konduktøren ...

does not have to mean only right now. It can mean:

• that is what I do in that situation
• that is what I will do if that happens

This is very normal in Danish, just as English sometimes says:

• If that happens, I ask him instead of
• If that happens, I will ask him

Hvis is the normal Danish word for if in conditional sentences.

Examples:

• Hvis det regner, bliver vi hjemme. = If it rains, we stay home.
• Hvis vi skal skifte spor ... = If we need to change track/platform ...

It is the standard choice here.

Yes. Hvor still means where here.

The whole part:

• hvor vi skal stige af

means:

• where we should get off

Even though it comes after spørger jeg konduktøren, it is still just an indirect question introduced by where.

In Danish, spor can be singular or plural depending on context and form, and in transport language it is often used in a general way.

Here, skifte spor is a fixed, natural expression meaning something like:

• change track
• switch to another track

Even though English might sometimes prefer tracks or platforms, Danish can use spor in this kind of compact expression.

Yes. A good way to read it is:

• Hvis vi skal skifte spor
  = If we need to change track/platform

• spørger jeg konduktøren
  = I ask the conductor

• hvor vi skal stige af
  = where we should get off

So the full structure is:

[If-clause] + [main clause] + [indirect question]

That makes the word order much easier to understand.

It sounds mostly neutral.

Nothing in it is especially slangy or highly formal. A native speaker could easily say it in normal conversation, especially in a travel situation.

The only small point is that stige af may sound a little more careful or bookish than stå af in some everyday contexts, but it is still completely natural and correct.