Soror rogat utrum fidicen cum choro canere velit.

Utrum introduces an indirect yes/no question. After rogat (asks), Latin often uses utrum to mean whether.

So:

• rogat = she asks
• utrum ... velit = whether ... wants

In direct speech, a yes/no question might also use utrum:

• Utrum fidicen canere vult? = Does the musician want to sing?

But here it is reported indirectly, so utrum means whether.

Because this is an indirect question, and Latin normally puts the verb of an indirect question in the subjunctive.

So:

• direct question: Utrum fidicen canere vult?
• indirect question: Soror rogat utrum fidicen canere velit.

That is why Latin uses velit rather than vult.

Fidicen is nominative singular here, and it is the subject of velit.

In other words, the musician is the one who wants to sing.

A native English speaker might expect the person after asks whether to feel a bit object-like, but in Latin the clause after utrum has its own grammar:

• fidicen = subject of velit
• canere = infinitive depending on velit

So the structure is basically:

• Soror rogat = The sister asks
• utrum fidicen ... velit = whether the musician wants ...

Because it depends on velit.

Latin uses volo (to want) with an infinitive, just like English uses want to + verb.

So:

• velit canere = wants to sing

Here canere is the present active infinitive of cano.

The understood subject of canere is fidicen.

Latin does not need to repeat the subject here. Since fidicen is the subject of velit, it is also naturally understood as the subject of canere:

• fidicen ... canere velit = the musician wants to sing

So it is the musician, not the sister, who would sing.

Because cum meaning with takes the ablative case.

So:

• chorus, chori = choir
• ablative singular = choro
• cum choro = with the choir

This is a very common Latin pattern:

• cum amico = with a friend
• cum magistro = with the teacher
• cum choro = with the choir

Rogat is the third person singular present active indicative of rogo.

Here it means:

• she asks

Since soror is singular and feminine, English naturally translates it as the sister asks or his/her sister asks, depending on context.

It does not mean asks for in this sentence. Instead, it introduces a question: asks whether ...

Yes. Soror is the main subject of the main verb rogat.

So the sentence has:

• main clause: Soror rogat = The sister asks
• subordinate clause / indirect question: utrum fidicen cum choro canere velit = whether the musician wants to sing with the choir

This is a good example of how Latin sentences can contain one clause inside another.

Because this is not a statement clause but an indirect question.

English says:

• She asks whether ...

Latin does the same kind of thing:

• rogat utrum ...

If it were a reported statement, Latin might use a different construction. But after rogat introducing a yes/no question, utrum is the natural choice.

The word order is fairly natural, but Latin word order is more flexible than English.

Here the order is:

• Soror = subject
• rogat = main verb
• utrum = introduces the indirect question
• fidicen = subject of the indirect question
• cum choro = prepositional phrase
• canere = infinitive
• velit = verb of the indirect question

One useful thing to notice is that velit comes at the end of its clause, which is very common in Latin. Even though the order differs from English, the cases and verb forms tell you how the sentence fits together.