Questo dato cambia il risultato.

Because dato here is a masculine singular noun.

• questo = this, for masculine singular nouns
• questa = this, for feminine singular nouns

So:

• questo dato = this piece of data / this datum
• questa data = this date

That is an important difference, because data in Italian usually means date, not data in the English sense.

Yes, but with a small difference from English.

In Italian:

• il dato = a datum / a piece of data
• i dati = data

English often uses data as a mass noun, but Italian commonly treats it as countable:

• un dato = one data point / one piece of data
• due dati = two data points / two pieces of data

So in this sentence, questo dato means this piece of data or this data point.

Italian uses definite articles more often than English does.

Here:

• il risultato = the result

Even when English might sometimes say simply changes the result or just changes results depending on context, Italian often keeps the article with a specific noun.

So cambia il risultato is the normal way to say changes the result.

Cambia is the third-person singular present tense of cambiare = to change.

The subject is questo dato, which is singular, so the verb must also be singular:

• questo dato cambia = this piece of data changes
• questi dati cambiano = these data points change

So the sentence is literally structured as:

• Questo dato = subject
• cambia = changes
• il risultato = the result

It can do both, depending on context.

It can be:

• intransitive: something changes
  
  • Il risultato cambia = The result changes
• transitive: something changes something else
  
  • Questo dato cambia il risultato = This piece of data changes the result

In your sentence, it is being used transitively, because il risultato is the direct object.

Because this is the normal Italian order:

• subject + verb + object

So:

• Questo dato = subject
• cambia = verb
• il risultato = object

This is very similar to standard English word order:

• This data point changes the result

Italian can change word order for emphasis, but the version you have is the most neutral and natural one.

Yes, but it does not mean exactly the same thing.

• Questo dato cambia il risultato = This piece of data changes the result
  
  • The data is presented as the thing causing the change.
• Il risultato cambia con questo dato = The result changes with this piece of data
  
  • The focus is more on the result and how it varies when this data is included.

Both can be correct, but the original sentence is more direct and causative.

Usually questo simply means this.

Italian has a basic contrast:

• questo = this
• quello = that

In everyday use, questo does not need any extra word to mean this one before a noun:

• questo dato = this data point

If you want to say this one by itself, you can say:

• questo = this one

Because of the structure.

Here, dato comes right after questo, so it is functioning as a noun:

• questo dato = this piece of data

The word dato can also be a past participle of dare = to give:

• ho dato = I gave / I have given

But in your sentence, that reading does not fit grammatically. After questo, the natural interpretation is clearly the noun dato.

The plural would be:

• Questi dati cambiano il risultato.

Changes:

• questo → questi for masculine plural
• dato → dati
• cambia → cambiano

So:

• Questo dato cambia il risultato. = This piece of data changes the result.
• Questi dati cambiano il risultato. = These data points change the result.

A simple pronunciation guide is:

• questo ≈ KWEH-stoh
• dato ≈ DAH-toh
• cambia ≈ KAHM-byah
• il risultato ≈ eel ree-zool-TAH-toh

A few helpful notes:

• qu in Italian is usually pronounced like kw
• ch in cambia is not present; the c before a is a hard k sound
• stress usually falls as follows:
  • QUES-to
  • DA-to
  • CAM-bia
  • risul-TA-to

Yes. Risultato usually means result, outcome, or sometimes score/result depending on context.

In this sentence, it most naturally means:

• the result
• the outcome

So the sentence could fit contexts like:

• an experiment
• a calculation
• a statistical model
• a report or analysis

Normally, no.

In this sentence, dato is a common noun, so it usually needs a determiner such as:

• questo dato = this data point
• un dato = a data point
• il dato = the data point / the datum

So Dato cambia il risultato would sound incomplete or incorrect in standard Italian.

Natural options are:

• Questo dato cambia il risultato.
• Il dato cambia il risultato.
• Un dato cambia il risultato.

depending on the meaning you want.