Learn Hardcore German: Vor dem Bewerbungsgespräch atme ich dreimal tief ein, damit ich ruhig und freundlich wirke. - Before the job interview I breathe in deeply three times so that I appear calm and friendly.

The preposition vor can take either accusative or dative.
With a time meaning (“before the job interview”), vor normally takes the dative.
Bewerbungsgespräch is a neuter noun: das Bewerbungsgespräch in the nominative.
Neuter dative singular is dem, so you get vor dem Bewerbungsgespräch.

If it were about location with movement towards something (“in front of the house”), vor could take accusative, but with time (“before X”), it’s dative.

What exactly is Bewerbungsgespräch? Is it one word? What gender is it?

Yes, Bewerbungsgespräch is a single compound noun.

die Bewerbung = application
das Gespräch = conversation, talk, interview

Put together: das Bewerbungsgespräch = job interview.
The gender of the whole compound is always the gender of the last part, so it’s neuter because Gespräch is neuter: das Bewerbungsgespräch.

Why does the sentence start with Vor dem Bewerbungsgespräch and then put the verb atme before ich? Why not just Ich atme ...?

German main clauses follow the “verb‑second” rule: the conjugated verb must be in second position.

You can put different elements in first position to emphasize them or organize the information differently.

Neutral: Ich atme vor dem Bewerbungsgespräch dreimal tief ein.
With emphasis on the time phrase: Vor dem Bewerbungsgespräch atme ich dreimal tief ein.

In the second version, Vor dem Bewerbungsgespräch is position 1, so atme has to be position 2, and the subject ich is pushed after the verb. This is normal and very common in German.

What is going on with atme ... ein? Why are atme and ein separated?

The base verb here is einatmen (“to breathe in”). This is a separable prefix verb.

Infinitive: einatmen
Present tense with ich: ich atme ein

In a normal main clause, the conjugated part (atme) goes to verb position 2, and the separable prefix (ein) moves to the end of the clause:

Ich atme dreimal tief ein.
Vor dem Bewerbungsgespräch atme ich dreimal tief ein.

In structures where the verb goes to the end (e.g. infinitives or subordinate clauses), the parts come back together: einzuatmen, weil ich tief einatme.

Why is the word order dreimal tief ein and not something like tief dreimal ein?

All of these are adverbials and verbal particles, and German has fairly stable “preferred” orders.

dreimal = how often? (frequency)
tief = how? (manner, describing how you breathe in)
ein = separable prefix, fixed at the very end of the clause

The usual pattern is: frequency → manner → separable prefix:

Ich atme dreimal tief ein.

Tief dreimal einatmen is not grammatical in this clause form, and Ich atme tief dreimal ein would sound wrong or at least very odd.

What does damit do here, and how is it different from um ... zu?

damit introduces a purpose clause (“so that / in order that ...”).

..., damit ich ruhig und freundlich wirke. = “... so that I appear calm and friendly.”

Difference to um ... zu:

um ... zu is used when the subject of both actions is the same:
- Ich atme dreimal tief ein, um ruhig und freundlich zu wirken.
damit is used when you want (or allow) different subjects, or when you prefer a full finite clause:
- Ich atme dreimal tief ein, damit ich ruhig und freundlich wirke.
- Ich atme dreimal tief ein, damit du dich entspannst. (different subjects → only damit works)

In your sentence, both are grammatically possible, but damit + finite clause is slightly more explicit and natural in many contexts.

Why does the verb wirke go to the end in damit ich ruhig und freundlich wirke?

damit introduces a subordinate clause. In German subordinate clauses, the conjugated verb goes to the very end of the clause.

Word order pattern:

conjunction – subject – (objects/adverbs) – verb (final)

So:

damit (conjunction)
ich (subject)
ruhig und freundlich (predicative adjectives)
wirke (conjugated verb at the end)

This contrasts with main clauses, where the verb is in second position.

Why is it wirke and not bin? What does wirken mean here exactly?

The verb wirken has a meaning “to appear / to come across / to seem (to others)”.

ich wirke ruhig ≈ “I appear calm / I come across as calm.”

sein (ich bin ruhig) talks about your actual state.
wirken focuses on how you are perceived by others.

So:

damit ich ruhig und freundlich bin = so that I am calm and friendly (as a fact)
damit ich ruhig und freundlich wirke = so that I come across as calm and friendly to other people

In the context of an interview, wirken is very natural, because you care about how you seem to your interviewer.

Why don’t ruhig and freundlich have endings like ruhige, freundliche?

Here ruhig and freundlich are predicate adjectives linked to the subject ich by the verb wirken.

Predicate adjectives in German do not take endings:

Ich bin müde. (not müder or müde-r)
Er wirkt nervös.
Sie bleibt freundlich.

Adjective endings appear mainly when the adjective comes directly before a noun:

ein ruhiger Mensch
eine freundliche Stimme

In your sentence, there is no noun after them, so no endings: ruhig und freundlich.

Why is there a comma before damit? Is it optional?

In German, every subordinate clause is separated from the main clause by a comma.

Since damit ich ruhig und freundlich wirke is a full subordinate clause, you must put a comma before damit:

..., damit ich ruhig und freundlich wirke.

This comma is not optional. Unlike English (where commas before “so that” can be flexible), in standard German the comma is required.

The interview is in the future, so why is the verb atme in the present tense and not some future form?

German uses the present tense (Präsens) very often for future events, especially when they are scheduled or clearly marked by a time expression.

Morgen gehe ich zum Arzt. = I’m going to the doctor tomorrow.
Nächste Woche fange ich einen neuen Job an.

Here the time phrase Vor dem Bewerbungsgespräch makes it clear we’re talking about a moment in the future (or a regular habit before any interview). So ich atme in the present is perfectly normal.

You could say werde ... atmen (Futur I), but that sounds heavier and is usually unnecessary in everyday German.

Could I say beim Bewerbungsgespräch or vor ich das Bewerbungsgespräch habe instead of vor dem Bewerbungsgespräch?

These options don’t mean the same thing and they follow different rules.

beim Bewerbungsgespräch = during the interview / at the interview
- Beim Bewerbungsgespräch atme ich dreimal tief ein.
  → I breathe in three times during the interview (different meaning).
You cannot say vor ich das Bewerbungsgespräch habe.
With a clause (“before I have the interview”), German uses bevor, not vor:
- Bevor ich das Bewerbungsgespräch habe, atme ich dreimal tief ein.

Your original uses vor + noun phrase in the dative:

Vor dem Bewerbungsgespräch atme ich ... = Before the interview (time phrase).

So:

vor dem Bewerbungsgespräch → preposition + noun (correct as given)
bevor ich das Bewerbungsgespräch habe → conjunction + clause (also correct, but longer and slightly different style).