Learn Hardcore German: Ich lege der Ärztin die Quittung vor und bekomme sofort Auskunft. - I present the receipt to the female doctor and immediately receive information.

Lege ... vor is the separable verb vorlegen (to present/submit a document to someone). Vor here is a separable prefix, not a standalone preposition. In main clauses the finite verb is in position 2 and the prefix goes to the end: Ich lege … vor. The whole verb is vorlegen.

Why is it der Ärztin instead of die Ärztin?

Because der Ärztin is dative feminine singular. With vorlegen, the person you present something to is the indirect object in the dative, and the thing presented is the direct object in the accusative:

Pattern: jemandem (Dat.) etwas (Akk.) vorlegen So: der Ärztin (to the doctor) + die Quittung (the receipt).

Why does the dative come before the accusative (/der Ärztin die Quittung)? Can I swap them?

Default order in German when both objects are full noun phrases is dative before accusative. You can swap, but it tends to sound marked or less natural unless there’s a reason (focus, pronoun vs. noun):

Natural: Ich lege der Ärztin die Quittung vor.
Also possible but less neutral: Ich lege die Quittung der Ärztin vor.
If one object is a pronoun, pronouns usually come earlier:
- Ich lege ihr die Quittung vor. (Dat. pronoun before Acc. noun)
- Ich lege sie der Ärztin vor. (Acc. pronoun before Dat. noun)

Where does the prefix go in subordinate clauses or with an infinitive?

In subordinate clauses the prefix rejoins the verb at the end:

…, dass ich der Ärztin die Quittung vorlege. With a zu-infinitive, the prefix stays attached:
…, um der Ärztin die Quittung vorzulegen.

Why is there no article before Auskunft?

German often uses certain abstract/result nouns without an article when they mean “some/any” in a generic sense. Auskunft behaves like that: Auskunt ≈ “information” (mass).

Ich bekomme sofort Auskunft = I get information immediately.
Using eine Auskunft is also possible but highlights a single, countable piece: Ich bekomme sofort eine Auskunft (über …).

Does bekommen mean “to become”?

No. Bekommen means “to receive/get.” “To become” is werden.

Ich bekomme Auskunft. = I receive information.
Ich werde müde. = I become tired.

Can I use kriegen or erhalten instead of bekomme?

Yes, but register shifts:

kriegen = colloquial: Ich kriege sofort Auskunft.
bekommen = neutral standard: Ich bekomme sofort Auskunft.
erhalten = more formal/bureaucratic: Ich erhalte sofort Auskunft.

Why is ich omitted in the second clause (… und bekomme …)?

German allows omission of a repeated subject in coordinated clauses when it’s the same subject. It remains understood that ich is the subject of both verbs. You can also repeat it for clarity or emphasis: … und ich bekomme … (also correct).

Is the placement of sofort correct? Where else could it go?

Yes. Sofort (a time adverb) is naturally placed early in the midfield:

Ich bekomme sofort Auskunft. (neutral and idiomatic) Other options:
Sofort bekomme ich Auskunft. (fronted for emphasis)
Ich bekomme Auskunft sofort. (rare/emphatic; sounds marked) With an article: Ich bekomme sofort eine Auskunft is fine but changes nuance.

What is the difference between Quittung, Rechnung, and Beleg?

Quittung: receipt acknowledging payment (proof that you paid).
Rechnung: invoice/bill requesting payment.
Beleg: generic proof/receipt (umbrella term; could be a Kassenbon, Quittung, etc.).

How do vorlegen, vorzeigen, zeigen, einreichen, and vorliegen differ?

vorlegen: present/submit a document officially to someone (often for checking). Pattern: jdm. etw. vorlegen.
vorzeigen: show something (usually physically, briefly), e.g., den Ausweis vorzeigen.
zeigen: to show (general).
einreichen: submit formally for processing (applications, forms), often to an office.
vorliegen: be on hand/available (intransitive): Die Unterlagen liegen vor.

What case is die Quittung here, and how can I tell?

Accusative feminine singular. It is the direct object (the thing being presented). The article die looks the same in nominative and accusative for feminine nouns, so you use the role in the sentence and the presence of the dative (der Ärztin) to tell.

How can I explicitly say who gives the information?

Add a von-phrase or change the verb to “give information”:

… und bekomme sofort Auskunft von ihr/von der Ärztin.
… und sie gibt mir sofort Auskunft.
Collocation: jdm. Auskunft geben/erteilen (someone gives information to someone).

Why is it Ärztin with an umlaut, and how is the feminine formed?

The masculine base is Arzt. The feminine is formed with -in and an umlaut: Ärztin. Plurals:

Feminine plural: Ärztinnen
Masculine plural: Ärzte
Inclusive pair often written: Ärztinnen und Ärzte

Do I need a comma before und here?

No. With a shared subject (Ich lege … und bekomme …), you must not insert a comma. If you repeat the subject (Ich lege …, und ich bekomme …), a comma before und is optional in modern German; many writers omit it unless the clauses are long or a pause aids readability.

Could I use Information(en) instead of Auskunft?

Often, yes, but nuance differs:

Auskunft (Auskünfte) is idiomatic for answers provided by a person/office to a query: Auskunft geben/erteilen/bekommen.
Information(en) is broader and common in written or general contexts; you’d typically use the plural: Informationen erhalten/bekommen. Your sentence with a similar meaning: … und bekomme sofort Informationen. (perfectly understandable, slightly less idiomatic than Auskunft in a service context).