Yo tampoco quiero salir esta noche.

Because yo adds emphasis or contrast.

Spanish often drops subject pronouns because the verb already shows who is doing the action:

• Quiero salir esta noche. = I want to go out tonight.

Adding yo makes it more like:

• I don’t want to either
• As for me, I don’t want to either

So in Yo tampoco quiero salir esta noche, yo is not required, but it sounds natural if the speaker is responding to someone else and wants to make their agreement clear.

Tampoco means neither or not ... either.

It is used when you are agreeing with a negative idea.

For example:

• No quiero salir. = I don’t want to go out.
• Yo tampoco. = Me neither. / I don’t either.

So in this sentence, tampoco shows that someone else has already said they do not want to go out, and the speaker is agreeing.

Because tampoco already carries the negative idea when it comes before the verb.

So:

• Yo tampoco quiero salir esta noche. = I don’t want to go out tonight either / Neither do I want to go out tonight.

This is normal Spanish.

You can also say:

• Yo no quiero salir esta noche tampoco.

That also means I don’t want to go out tonight either, but the structure is a bit different. In your sentence, tampoco comes before the verb and works as the negative agreement word by itself.

A useful rule:

• también = also, too, in positive contexts
• tampoco = neither, not ... either, in negative contexts

Yes.

If someone says something negative, you can answer with:

• Yo tampoco. = Me neither.

And if you want to repeat the whole idea, you can say:

• Yo tampoco quiero salir esta noche.

So this sentence is basically an expanded version of Yo tampoco.

Because after querer + another verb, Spanish uses the infinitive directly, with no extra word like English to.

So:

• quiero salir = I want to go out
• quiero comer = I want to eat
• quiero dormir = I want to sleep

In English, we say want to go out, but in Spanish it is simply:

• querer + infinitive

No a is used here.

Quiero is the first person singular present tense form of querer.

• querer = to want
• quiero = I want

This verb is stem-changing in the present tense:

• yo quiero
• tú quieres
• él/ella quiere
• nosotros queremos
• vosotros queréis
• ellos quieren

Notice that the e changes to ie in most forms.

Here salir means to go out.

Depending on context, salir can mean:

• to go out
• to leave
• to head out

In this sentence, with esta noche, it most naturally means go out tonight, often in the sense of going out socially, going out somewhere, or leaving the house.

In Spain, salir is very commonly used this way.

Literally, esta noche is this night, but in natural English the usual translation is tonight.

Spanish often uses this structure for time expressions:

• esta mañana = this morning
• esta tarde = this afternoon / this evening
• esta noche = tonight

So even though the words are literally this night, the natural meaning is tonight.

Because esta is a demonstrative determiner, and it already fills the role that the article would normally fill.

So Spanish says:

• esta noche = this night / tonight

Not:

• la esta noche

This is the same pattern as:

• este libro = this book
• esa casa = that house

You use this/that-type words instead of the, not together with it.

No, that sounds wrong in standard Spanish.

Use:

• también for positive agreement
• tampoco for negative agreement

Compare:

• Quiero salir esta noche. — Yo también.
  I want to go out tonight. — Me too.

• No quiero salir esta noche. — Yo tampoco.
  I don’t want to go out tonight. — Me neither.

So in your sentence, tampoco is the correct word.

Yes, but the original sentence is the most neutral and natural one.

Standard version:

• Yo tampoco quiero salir esta noche.

Other possible versions include:

• Tampoco quiero salir esta noche.
• Yo no quiero salir esta noche tampoco.

These are all possible, but they do not feel exactly the same.

• Yo tampoco quiero salir esta noche strongly shows agreement with someone else’s negative statement.
• Yo no quiero salir esta noche tampoco sounds more like a full negative sentence with either added at the end.

So the version you have is a very natural choice.

Yes.

• esta noche = tonight → one specific night, the current one
• por la noche = at night / in the evening → more general

Compare:

• No quiero salir esta noche. = I don’t want to go out tonight.
• No quiero salir por la noche. = I don’t want to go out at night.

So esta noche is specific, while por la noche is more general or habitual.

Yes, completely natural.

A speaker in Spain would easily say:

• Yo tampoco quiero salir esta noche.

It sounds everyday, idiomatic, and conversational. It is exactly the kind of sentence you might hear when friends are discussing plans and someone agrees that they also do not feel like going out.