Ho lavorato tutta la mattina.

Italian often expresses the past with a two-part tense called the passato prossimo:

• ho = present tense of avere for io
• lavorato = past participle of lavorare

So ho lavorato literally looks like I have worked, but in normal English it is often translated simply as I worked, depending on context.

In this sentence, the speaker is talking about a completed stretch of work in the past: all morning.

Because lavorare normally takes avere in compound tenses.

So:

• ho lavorato = correct
• sono lavorato = not correct

In Italian, some verbs use essere and others use avere in the passato prossimo. Most transitive verbs use avere, and many intransitive verbs do too. Lavorare is one of the verbs that uses avere.

Lavorato is the past participle of lavorare.

The three main parts are:

• lavorare = to work
• lavoro = I work
• lavorato = worked

In compound tenses such as ho lavorato, the past participle combines with an auxiliary verb:

• ho lavorato
• hai lavorato
• abbiamo lavorato

Because tutta agrees with mattina, which is a feminine singular noun.

So:

• tutto il giorno = all day
  
  • giorno is masculine singular
• tutta la mattina = all morning
  
  • mattina is feminine singular

The form of tutto changes to match the noun:

• tutto
  • masculine singular
• tutta
  • feminine singular
• tutti
  • masculine plural
• tutte
  • feminine plural

With tutto meaning all / the whole, Italian normally uses the definite article:

• tutta la mattina
• tutto il giorno
• tutta la settimana

So tutta la mattina means the whole morning or all morning.

This is different from English, where we often just say all morning without an article.

No. Here it means the whole morning on one specific occasion.

So:

• Ho lavorato tutta la mattina = I worked all morning
• Lavoro tutte le mattine = I work every morning

That is an important difference:

• tutta la mattina = one whole morning
• tutte le mattine = every morning / all mornings

Yes, you can.

Both are possible:

• Ho lavorato tutta la mattina
• Ho lavorato per tutta la mattina

The version without per is very common and natural.
Adding per can make the duration a little more explicit, like for the whole morning, but in many contexts it is not necessary.

Because ho lavorato and lavoravo do not mean exactly the same thing.

• ho lavorato = completed action in the past, viewed as a whole
• lavoravo = imperfect; often used for background, repeated actions, habits, or actions in progress in the past

Compare:

• Ho lavorato tutta la mattina.
  The speaker presents the morning’s work as a completed block.

• Lavoravo tutta la mattina quando mi hai chiamato.
  I was working all morning when you called me.

• Da giovane lavoravo tutte le mattine.
  When I was young, I used to work every morning.

So in your sentence, ho lavorato is the natural choice for a finished period of work.

No. The h in ho is silent.

So ho is pronounced essentially like o.

The h is there mainly to distinguish it in writing from o, which can mean or.

For example:

• ho lavorato = I worked / I have worked
• pane o pasta = bread or pasta

Yes, although the original order is the most neutral and common:

• Ho lavorato tutta la mattina.

You may also hear or see:

• Tutta la mattina ho lavorato.
• Ho tutta la mattina lavorato. — possible, but not the normal everyday order

Putting tutta la mattina first can add emphasis, as if the speaker wants to stress the duration.

Usually, yes.

Ho lavorato tutta la mattina normally suggests that the speaker is looking back on the morning as a completed time span.

That does not always mean the person is done working for the day; it just means that the morning period is being treated as complete.

If the action were still in progress, Italian would usually use a different structure, such as:

• Sto lavorando da tutta la mattina in informal speech
• more naturally: Lavoro da tutta la mattina or Sto lavorando da stamattina

Sometimes, yes, but the structure changes.

You could say:

• Ho lavorato tutta la mattina = I worked all morning
• Ho lavorato tutta stamattina = I worked all this morning

Both are natural, but stamattina specifically refers to this morning, while la mattina here refers to the whole morning as a time span.

So the choice depends on whether you want to stress this morning in particular.

Not here.

With avere, the past participle usually does not change for gender or number:

• Io ho lavorato
• Lei ha lavorato
• Noi abbiamo lavorato

So a man and a woman both say:

• Ho lavorato

Agreement is a different issue from cases with essere, where the participle often does agree:

• Sono andato / Sono andata

But with lavorare in ho lavorato, no change is needed.