Learn Hardcore Norwegian: Du er alltid velkommen her.

You can approximate it in English as
“doo air AHL-teed VEL-koh-men hair.”
Breakdown:
• Du – /dʉː/ (like French u or German ü)
• er – /ær/ (similar to English air, short e)
• alltid – /ˈɑlːtiːd/ (double l is long, tid rhymes with “teed”)
• velkommen – /ˈvɛlkɔmən/ (stress on vel-)
• her – /heːr/ (long e, like “hair” but more closed)

Why does alltid come after er and before velkommen?

In Norwegian main clauses, adverbs of frequency/time like alltid normally follow the finite verb. The typical word order is:
Subject – finite verb – adverb of frequency – complement
So Du (subject) + er (verb) + alltid (adverb) + velkommen her (complement).

Why is it velkommen and not velkomment or velkomne?

Velkommen here is an adjective agreeing with a singular common-gender subject (du). Norwegian adjective endings:
• Indefinite singular common – no ending → velkommen
• Indefinite singular neuter – add -t → velkomment (e.g., et velkomment tiltak)
• Indefinite plural – add -e → velkomne (e.g., gjestene er velkomne)
Since du is singular, you use velkommen.

What’s the difference between her and hit, and why is it her here?

• Her indicates a static location (“right here”).
• Hit indicates movement toward here (“come here”).
In Du er alltid velkommen her, you’re talking about being welcome in this place (no movement), so you use her.

Can I drop du er and just say alltid velkommen her?

Yes, especially on signs or in brief invitations you often see Alltid velkommen or Alltid velkommen her. In everyday speech, though, you normally include the subject and verb: Du er alltid velkommen her.

How do you turn Du er alltid velkommen her into a question?

Invert the finite verb and the subject:
Er du alltid velkommen her?
That means “Are you always welcome here?”

Is velkommen in this sentence an adjective or a past participle?

Here velkommen is a predicative adjective describing a state (“you are welcome”). It is not the past participle of a verb. The verb phrase å ønske noen velkommen (“to welcome someone”) would have ønsket velkommen as its perfect form.

What part of speech is alltid?

Alltid is an adverb of frequency meaning always. It never changes form.

How would I address a group instead of one person?

Use the plural pronoun dere and the plural adjective ending -e:
Dere er alltid velkomne her
That means “You (all) are always welcome here.”

What about the formal “you”? How would I say “You are always welcome here” politely?

The formal singular pronoun is De (capital D in writing). You would say:
De er alltid velkommen her
Question form by inversion: Er De alltid velkommen her?
Note that formal De is quite rare in modern spoken Norwegian; most people just use du.

How can I add extra warmth, like “warmly welcome”?

You can insert words like hjertelig or varmt before velkommen:
Du er alltid hjertelig velkommen her
Du er alltid varmt velkommen her
Hjertelig velkommen (“heartily welcome”) is especially common when you want to sound especially sincere.