L'opposizione va al giudice di pace.

Because la becomes l' before a feminine noun starting with a vowel.

• la opposizione → l'opposizione

This is called elision. It is very common in Italian:

• l'amica
• l'idea
• l'acqua

So opposizione is a feminine singular noun, and before it the article is shortened to l'.

Yes. Va is the third-person singular of andare.

• andare → va

But here it does not sound like physical movement in the everyday sense. In legal or formal language, andare a can mean something like:

• is to be filed with
• goes to
• must be submitted to

So this is a good example of Italian using a very common verb in a more formal, procedural way.

Because al = a + il.

• a = to
• il = the
• a + il → al

This is a standard contraction of a preposition plus article in Italian. Similar combinations are:

• a + lo = allo
• a + la = alla
• a + i = ai
• a + gli = agli
• a + le = alle

So al giudice literally contains both to and the.

Because giudice di pace is a fixed legal title.

In many Italian job titles or institutional names, di is used in this way without meaning a full English of the word-for-word translation. It behaves like a set expression.

So you should learn giudice di pace as a whole unit, just like a title.

Because in the fixed expression giudice di pace, the noun pace appears without an article.

This is normal in many Italian titles and set phrases. Not every noun after di needs an article. Compare the general pattern of expressions like:

• camera di commercio
• ufficio di polizia
• giudice di pace

So di pace functions as part of the title, not as an ordinary phrase where you would automatically expect della.

Grammatically, it is in the present tense:

• va = goes

But in formal, legal, or administrative language, the present tense often expresses:

• a rule
• a procedure
• an instruction
• what is required

So even though it is structurally present tense, its force can feel like:

• should be submitted
• is to be brought
• must go

This kind of present tense is very common in official Italian.

Yes, deve andare is possible in some contexts, but it is not exactly the same in tone.

• va al giudice di pace sounds more formal, procedural, and impersonal
• deve andare al giudice di pace sounds more explicitly like must go

Legal and bureaucratic Italian often prefers the more compact style with the simple present, because it sounds more like a rule or formal direction.

Yes. Opposizione is a feminine singular noun.

You can tell from:

• the article l', which here stands for la
• related forms such as questa opposizione and un'opposizione

Many Italian nouns ending in -zione are feminine:

• informazione
• situazione
• decisione is feminine too, though it ends differently

So if you use adjectives with opposizione, they must be feminine singular as well.

That is correct: nouns ending in -e can be masculine or feminine. You usually learn their gender from the article or from usage.

Here:

• il giudice = masculine singular

But giudice can refer to a female judge too; the grammatical article may change depending on the speaker and context:

• il giudice
• la giudice in some modern usage
• sometimes other forms may appear depending on style and convention

In this sentence, the important thing is that giudice di pace is the standard title, and here it appears with al, which comes from a + il, so the grammar is masculine singular.

Yes, but the given order is the most neutral and natural in this kind of formal statement:

• L'opposizione va al giudice di pace.

Italian can sometimes move elements around for emphasis, but that usually changes the tone or sounds marked. For example:

• Va al giudice di pace l'opposizione.

That is possible in some contexts, but it is less neutral and may sound more literary, emphatic, or context-dependent.

So for normal learning purposes, the original order is the one to remember.

Because in ordinary Italian running text, job titles and institutional roles are often written in lowercase:

• il giudice di pace
• il presidente
• il ministro

Capital letters may appear in very formal documents, headings, or institutional styles, but lowercase is normal and correct in standard prose.

So giudice di pace in lowercase is not a mistake.