Der Supermarkt liefert außerdem Getränke bis an die Tür.

It’s a sentence adverb meaning “in addition/besides,” linking this statement to something previously mentioned. In main clauses, the finite verb must be in position 2 (the V2 rule). You can place außerdem either:

• at the start: Außerdem liefert der Supermarkt Getränke bis an die Tür.
• in the middle field after the verb: Der Supermarkt liefert außerdem Getränke bis an die Tür.

You cannot put it between subject and finite verb, so not: Der Supermarkt außerdem liefert … (wrong).

Often, yes, but with a nuance:

• außerdem is a sentence-level connector (“what’s more, in addition”) and sounds a bit more formal/logical.
• auch is a focusing adverb (“also, too”) and usually appears near the element it adds: Der Supermarkt liefert auch Getränke bis an die Tür.

Both are fine; außerdem stresses the addition of a whole statement, while auch highlights the added item.

Both are correct, with a slight nuance:

• bis an die Tür (with an
  • accusative for motion) suggests “right up to (touching/at) the door.”
• bis zur Tür is a contraction of bis zu der Tür (with zu
  • dative) and means “as far as the door,” slightly less contact-focused.

In everyday use, the difference is small; choose either unless you want to emphasize “right up to it,” in which case bis an die Tür fits well.

Accusative. an is a two-way preposition (Wechselpräposition): it takes

• accusative with motion toward a goal: an die Tür
• dative for location: an der Tür

Since the delivery involves movement to the door, it’s an die Tür (accusative). Note: bis itself doesn’t assign case; the following preposition does.

Because it’s an indefinite plural direct object (generic “drinks/beverages”). In German, bare plural nouns are common when speaking generally:

• General: Der Supermarkt liefert Getränke …
• Specific (previously mentioned/known): Der Supermarkt liefert die Getränke …

• liefern: to deliver (general term).
• ausliefern: to deliver/ship out to the recipient (often logistics/fulfillment).
• anliefern: to deliver to a place/recipient (focus on bringing goods to a location).
• zuliefern: to supply components/parts (B2B supply chain).

In your sentence, liefern is the natural, broad choice.

It depends on the nuance:

• bis an die Tür: right up to (at) the door.
• bis vor die Tür: up to in front of the door (stops in front; doesn’t necessarily touch or reach the door surface/threshold).

Delivery services often use bis zur Haustür or bis vor die Haustür.

Yes, it’s feminine.

• Singular: die Tür (nom/acc), der Tür (dat), der Tür (gen)
• Plural: die Türen (nom/acc), den Türen (dat), der Türen (gen) Common compound: die Haustür (front door).

Place it before the destination phrase:

• Der Supermarkt liefert außerdem Getränke direkt an die Tür.
• or fronted: Außerdem liefert der Supermarkt Getränke direkt an die Tür.