Eu sempre salvo o documento antes de fechar o programa.

Yes. Portuguese often allows the subject pronoun to be omitted because the verb form already shows who is doing the action.

So:

• Eu sempre salvo o documento...
• Sempre salvo o documento...

Both are natural.

Including eu can make the sentence a little clearer or slightly more emphatic. In Brazilian Portuguese, subject pronouns are used more often than in some other varieties, so eu sounds completely normal here.

Sempre is an adverb, and in Portuguese adverbs like this often go before the main verb:

• Eu sempre salvo o documento.

This is the most neutral, natural order.

You can also hear:

• Sempre salvo o documento...

That is also correct. The version with eu sempre is just very common and straightforward.

Salvo is the 1st person singular present indicative of salvar.

• eu salvo = I save

In this sentence, the present tense expresses a habitual action:

• Eu sempre salvo o documento... = I always save the document...

So it means this is something the speaker regularly does, not just something happening right now.

Yes. Salvo can also mean except for or safe/saved in other contexts.

For example:

• Salvo engano... = Unless I’m mistaken...
• Ele está salvo. = He is safe / saved.

But in Eu sempre salvo o documento, it is clearly the verb salvar because:

• it follows eu
• it matches a present-tense verb form
• it has a direct object: o documento

So here it definitely means I save.

Portuguese uses definite articles more often than English.

So where English might say:

• I save the document before closing the program

Portuguese naturally says:

• salvo o documento antes de fechar o programa

The articles o... o... make the nouns sound specific and natural. Omitting them here would usually sound incomplete or unnatural in normal speech.

Because after antes de (before), Portuguese normally uses the infinitive.

So:

• antes de fechar o programa = before closing the program / before I close the program

This is a very common structure:

• antes de sair = before leaving
• antes de dormir = before sleeping
• antes de abrir o arquivo = before opening the file

Because after the preposition de, Portuguese uses the infinitive, not the conjugated form.

• fechar = to close
• fecho = I close

So:

• antes de fechar o programa = correct
• antes de fecho o programa = incorrect

A good shortcut is: after antes de, expect an infinitive.

It can express either idea in English.

In Portuguese, when the subject is the same as the main clause, the infinitive is very common:

• Eu sempre salvo o documento antes de fechar o programa.

This naturally implies that I am the one closing the program.

If you want to make the subject explicit, you could say:

• antes de eu fechar o programa

But in this sentence, that is not necessary.

You usually keep it if you want the full idea before closing the program.

But you could change the noun depending on context:

• antes de fechar o arquivo = before closing the file
• antes de fechar a janela = before closing the window
• antes de sair do programa = before exiting the program

For software, fechar o programa is very natural in Brazilian Portuguese.

Yes. In Brazilian Portuguese, salvar is the standard and most common verb for saving files, documents, and computer work.

Examples:

• Salvar o arquivo
• Salvar o documento
• Clique em salvar

You may also see guardar in other contexts, but for computers and software, salvar is the usual choice.

Yes, very natural:

• Sempre salvo o documento antes de fechar o programa.

That sounds perfectly normal.

If you include eu, it may feel a bit more personal, explicit, or contrastive:

• Eu sempre salvo o documento...
  maybe implying I do this, even if others don’t

So both are good; the difference is mostly about style and emphasis.

In Brazilian Portuguese, salvo is roughly:

• SAHL-voo

A few helpful notes:

• sal- has an a like in father
• v is a real v sound
• the final o in Brazilian Portuguese is often pronounced like oo

So it sounds approximately like SAHL-voo, though not exactly like English sounds.

A little, yes. Portuguese allows some flexibility, but some versions sound more natural than others.

Very natural:

• Eu sempre salvo o documento antes de fechar o programa.
• Sempre salvo o documento antes de fechar o programa.

Less neutral, but possible in special contexts:

• O documento eu sempre salvo antes de fechar o programa.

That last version emphasizes o documento.

So the original sentence is the most neutral and standard way to say it.