Á morgnana vill hún frekar rúsínur, en ég vil frekar hnetur.

No. Á morgnana means in the mornings or every morning / mornings in general.

A very easy thing to mix up is:

• á morgun = tomorrow
• á morgnana = in the mornings

So this sentence is talking about a habit, not about one specific morning.

Icelandic often uses the definite plural in time expressions when talking about something habitual or repeated.

So:

• á morgnana = in the mornings
• á kvöldin = in the evenings
• á næturnar = at night / in the nights

It may feel a bit like on the mornings literally, but idiomatically it means in the mornings.

Because Icelandic follows the V2 rule in main clauses: the finite verb normally comes in the second position.

Here, the first element is Á morgnana, so the verb vill must come next:

• Á morgnana
  • vill
    • hún

That is why the subject hún comes after the verb.

Compare:

• Hún vill frekar rúsínur.
• Á morgnana vill hún frekar rúsínur.

Both are correct, but the second one fronts the time phrase.

These are just different present-tense forms of the verb vilja (to want).

Relevant forms here are:

• ég vil = I want
• hún vill = she wants

So:

• hún vill
• ég vil

The extra l is simply part of the 3rd person singular form.

Yes, more or less. Literally, vilja frekar is like want rather, but in natural English it is usually best translated as prefer.

So:

• hún vill frekar rúsínur = she prefers raisins
• ég vil frekar hnetur = I prefer nuts

This is a very normal way to express preference in Icelandic.

Here frekar means rather, preferably, or more readily.

In this sentence it shows preference:

• frekar rúsínur = rather raisins
• frekar hnetur = rather nuts

In smoother English, that becomes prefer raisins and prefer nuts.

That position is very natural in Icelandic when frekar modifies the choice being made.

So the pattern is:

• subject + vilja + frekar + thing

Examples:

• Ég vil frekar kaffi.
• Hún vill frekar te.

Other word orders are sometimes possible for emphasis, but this is a standard, natural placement.

They are the direct objects of vilja, so they are in the accusative.

In this sentence:

• rúsínur = accusative plural
• hnetur = accusative plural

For these feminine nouns, the nominative plural and accusative plural happen to look the same, so you do not see a form change here.

Because the sentence is talking about raisins and nuts in a general or indefinite sense, not about specific raisins or specific nuts already known to both speakers.

So Icelandic, like English, simply uses the bare plural:

• rúsínur = raisins
• hnetur = nuts

If you wanted the raisins or the nuts, Icelandic would normally mark that with the definite article attached to the noun.

Because each clause expresses its own preference:

• hún vill frekar rúsínur
• ég vil frekar hnetur

Repeating frekar makes the contrast clear and balanced. It is similar to English:

• She prefers raisins, but I prefer nuts.

You could sometimes omit repeated material in conversation if the meaning is obvious, but this full version is very natural and clear.

Here en means but.

It connects two contrasting ideas:

• she prefers raisins
• but I prefer nuts

So the sentence is contrasting her preference with my preference.

Yes. That is also grammatical.

The difference is mainly emphasis:

• Á morgnana vill hún frekar rúsínur
  → puts in the mornings first, making the time frame the topic

• Hún vill frekar rúsínur á morgnana
  → starts with she, so it feels a bit more neutral

Icelandic allows this kind of movement, but when you move something to the front, the V2 word order affects the rest of the clause.