Learn Hardcore Indonesian: Silakan bertanya sekarang; pertanyaan apa pun akan dijawab singkat. - Please ask now; any question will be answered briefly.

silakan: a polite invitation/permission (“please, go ahead”). It doesn’t sound like you’re asking for a favor.
tolong: a request for help (“please help by …”), e.g., Tolong kirim email.
mohon: very formal, humble request, often in writing or announcements, e.g., Mohon menunggu.
harap: formal/impersonal “please” used on signs/instructions, e.g., Harap tenang.
mari: “let’s,” inviting joint action, e.g., Mari mulai.

Why use bertanya instead of tanya? Are both correct?

Both are correct, but differ in tone:

bertanya is the standard intransitive verb “to ask (a question).” More neutral/formal: Silakan bertanya.
tanya is root/colloquial verb; perfectly natural in casual speech: Silakan tanya.
Related forms: menanyakan (sesuatu) kepada (seseorang) = to ask about something (to someone). menanya is rare.

How natural is the semicolon here? Could I just use a period or comma?

A semicolon is fine and a bit formal in Indonesian, linking two closely related clauses. Alternatives:

Period (most common): Silakan bertanya sekarang. Pertanyaan apa pun akan dijawab singkat.
Comma appears in informal writing, though prescriptively less ideal for two full clauses.

Why is apa pun two words? When is pun attached?

pun is a particle. It’s written separately when it means “-ever/any,” as in apa pun, siapa pun, kapan pun, di mana pun. It’s attached in certain fixed words like walaupun, meskipun, biarpun, ataupun, adapun, andaipun. So here, apa pun must be two words.

What’s the difference between apa pun and apa saja/apa aja?

apa pun: “no matter what,” an unrestricted, sweeping allowance. Strong, slightly formal/neutral.
apa saja/apa aja: “any (of various),” highlighting variety/options; more conversational with aja. In this sentence, pertanyaan apa pun feels firm and comprehensive; pertanyaan apa saja feels a bit more casual/flexible.

Does pertanyaan apa pun imply singular or plural? Do I need to mark plurality?

Indonesian usually doesn’t mark plural. pertanyaan apa pun can mean “any question” or “any questions.” You don’t need reduplication here. If you want to stress inclusivity, you can say semua pertanyaan (“all questions”).

Is akan necessary? What changes if I omit it?

akan marks futurity/intent. Without it, dijawab can mean a general promise or near-future understood from context. All are possible:

With future nuance: … akan dijawab …
Neutral/generic: … dijawab …
Informal future: … bakal dijawab …

In akan dijawab, where is the agent? How would I say “I/we will answer”?

It’s an agentless passive (very common), focusing on the questions. To name the agent:

Passive with agent fronted: Pertanyaan apa pun akan saya/kami jawab singkat.
Passive with oleh: Pertanyaan apa pun akan dijawab singkat oleh kami. (more formal/stiff)
Active: Kami akan menjawab semua pertanyaan secara singkat.

Is singkat acting like an adverb here? Should it be secara singkat?

Yes, singkat functions as a manner complement, which is natural in Indonesian. You can also say:

… akan dijawab secara singkat. (more formal)
… akan dijawab singkat saja. (colloquial “just briefly”) dengan singkat is understood but less common than secara singkat or bare singkat.

singkat vs ringkas vs pendek — which sounds best with answers?

singkat = brief/short in duration or length; very common: jawaban singkat.
ringkas = concise/compact (well-compressed content); also good: jawaban ringkas.
pendek = short (physical/temporal length); jawaban pendek appears in school contexts (“short-answer”), but for style, singkat/ringkas sound more natural.

Any nuances with sekarang? How about segera or sekarang juga?

sekarang = now (neutral).
sekarang juga = right now, adds urgency.
segera = soon/shortly/immediately (context-dependent; not necessarily “this very moment”).
kini = now/at present (more literary/formal).

Is the word order fixed? Can I say Silakan sekarang bertanya?

Time adverbs are flexible. Options:

Neutral: Silakan bertanya sekarang.
Emphatic fronting: Sekarang, silakan bertanya.
Silakan sekarang bertanya is possible but less common than the two above.

Can I drop pertanyaan and just say Apa pun akan dijawab singkat?

Better keep pertanyaan. Apa pun alone means “anything,” which is too broad/ambiguous. Pertanyaan apa pun clearly restricts the scope to questions.

Is the capitalization after the semicolon correct?

Yes. After a semicolon, Indonesian continues with lowercase (unless a proper noun). Spacing is also correct: no space before the semicolon, one space after.

Could you give casual and more formal rewrites that sound natural?

Casual: Tanya aja sekarang; pertanyaan apa pun bakal aku jawab singkat.
Neutral: Silakan tanya sekarang; pertanyaan apa pun akan saya jawab singkat.
More formal: Silakan mengajukan pertanyaan sekarang; semua pertanyaan akan kami jawab secara ringkas.