Originalpressingen har plateomslaget og inneromslaget.

Because Norwegian usually writes compound nouns as one word, where English often uses two.

So:

• original
  • pressing → originalpressing
• and then the definite ending is added:
  • originalpressingen = the original pressing

This is very common in Norwegian. If you split compound nouns the way English does, it often looks wrong in Norwegian.

The ending -en marks the noun as definite singular.

So:

• en originalpressing = an original pressing
• originalpressingen = the original pressing

In Norwegian, the definite article is usually added to the end of the noun, instead of being a separate word like English the.

Those nouns are also in the definite singular, but they are neuter nouns.

In Bokmål:

• common gender nouns often take -en in the definite singular
• neuter nouns often take -et in the definite singular

So:

• et plateomslag → plateomslaget
• et inneromslag → inneromslaget

That is why you see:

• originalpressingen with -en
• plateomslaget and inneromslaget with -et

Because Norwegian normally puts definiteness on the noun itself.

Compare:

• English: the original pressing

• Norwegian: originalpressingen

• English: the record sleeve
• Norwegian: plateomslaget

So the idea of the is already built into the endings -en and -et.

A separate article like den/det is usually only added in other structures, especially when an adjective comes before the noun, for example:

• det gamle plateomslaget = the old record sleeve

But in your sentence there is no adjective before plateomslaget or inneromslaget, so no separate article is needed.

They are both compound nouns.

plateomslag

• plate = record / disc
• omslag = cover / sleeve / wrapping

So plateomslag means the record cover / album sleeve.

inneromslag

• inner = inner
• omslag = cover / sleeve

So inneromslag means the inner sleeve.

The exact English translation depends on context, but for vinyl records:

• plateomslaget = the outer sleeve / cover
• inneromslaget = the inner sleeve

Har is the present tense of ha, which means to have.

So:

• ha = to have
• har = have / has

In this sentence:

• Originalpressingen har plateomslaget og inneromslaget
• = The original pressing has the record sleeve and the inner sleeve

English uses has because the subject is singular, but Norwegian uses har for all persons:

• jeg har = I have
• du har = you have
• han har = he has
• de har = they have

This is the normal Norwegian word order for a basic statement:

subject + verb + object

So here:

• Originalpressingen = subject
• har = verb
• plateomslaget og inneromslaget = object

It works very much like English:

• The original pressing
  • has
    • the record sleeve and the inner sleeve

Nothing unusual is happening with the word order in this sentence.

Often, yes, depending on context.

In record-collecting language, originalpressing usually refers to an original pressing, which may overlap with the idea of a first pressing, though they are not always exactly the same in every context.

So:

• originalpressing = original pressing
• sometimes close in meaning to first pressing

If you are translating for collectors, it is best to keep the distinction that the Norwegian sentence actually uses: original pressing.

The indefinite singular forms are:

• en originalpressing = an original pressing
• et plateomslag = a record sleeve / cover
• et inneromslag = an inner sleeve

Then the definite singular forms are:

• originalpressingen = the original pressing
• plateomslaget = the record sleeve / cover
• inneromslaget = the inner sleeve

This is a very useful pattern to learn:

• en noun → noun + -en
• et noun → noun + -et

Yes. Og simply means and.

So:

• plateomslaget og inneromslaget
• = the record sleeve and the inner sleeve

It joins the two objects of har.

A plural version would depend on exactly what you want to say, but here is the basic idea.

Singular:

• plateomslaget = the record sleeve
• inneromslaget = the inner sleeve

Plural indefinite:

• plateomslag = record sleeves
• inneromslag = inner sleeves

Plural definite:

• plateomslagene = the record sleeves
• inneromslagene = the inner sleeves

So if you wanted to say The original pressings have the record sleeves and the inner sleeves, you could say:

• Originalpressingene har plateomslagene og inneromslagene

That sentence is less likely in real-life use unless you are talking about several specific pressings and several specific sleeves, but it shows how the forms work.

Yes, it is natural, especially in a collector, sales, or catalog description context.

It sounds like the kind of sentence you might see when describing the condition or completeness of a vinyl release:

• the original pressing
• includes the outer sleeve
• and the inner sleeve

So grammatically and stylistically, it fits well in that kind of context.