Learn Hardcore Indonesian: Setelah rapat, kami jalan-jalan sebentar dan ketawa bersama. - After the meeting, we take a short stroll and laugh together.

kami excludes the listener (we but not you). That fits the sentence if the listener didn’t join.
kita includes the listener (we including you). Use this only if you’re talking to someone who was also there.

Is ketawa informal? Should I use tertawa instead?

Yes. ketawa is casual/colloquial; tertawa is the standard/formal form. Your sentence is neutral–casual overall. A more formal version would use tertawa.

What does jalan-jalan mean, and how is it different from berjalan or berjalan-jalan?

jalan-jalan: to stroll/go out for fun/hang out (leisure activity).
berjalan: to walk (move on foot), not necessarily for leisure.
berjalan-jalan: standard/formal equivalent of jalan-jalan. Meaning is the same; tone is more formal.

Why is there a hyphen in jalan-jalan?

The hyphen marks reduplication, which often turns a basic word into an activity or gives a “casual/multiple” nuance. Standard writing uses a hyphen: jalan-jalan. In texting, you might see “jalan2,” but that’s informal.

Does sebentar apply to both actions (jalan-jalan and ketawa), or just the first?

By default, sebentar attaches to the phrase right before it, so it most naturally modifies jalan-jalan. If you want it to modify both, you could say:

kami jalan-jalan dan ketawa sebentar-sebentar (both briefly) — though this sounds a bit odd.
kami jalan-jalan sebentar dan juga ketawa sebentar (explicit). If only the laughing was brief, put sebentar after ketawa: kami jalan-jalan dan ketawa sebentar.

Can I place sebentar somewhere else?

Yes:

kami sebentar jalan-jalan is possible in speech but can sound clunky.
kami jalan-jalan sebentar saja adds “just/a bit.”
sempat is natural for a brief opportunity: Setelah rapat, kami sempat jalan-jalan sebentar.

Can I use sesudah or habis instead of setelah? Any difference?

setelah and sesudah are near-synonyms; setelah can feel a touch more formal for some speakers.
habis/abis is colloquial: Habis rapat, kami ...
Formal/literary alternatives: usai rapat, selesai rapat.

Do I need something like “sudah” to show past tense?

No. Indonesian doesn’t mark tense on verbs. Setelah already sets a past-sequence context. If you want to be explicit about recency or time:

tadi (earlier today), kemarin (yesterday), barusan (just now), sudah (already) can be added as needed.

Is dan the best connector here? What about lalu/terus/kemudian?

dan simply links two actions (“and”).
lalu/kemudian (“then”) emphasize sequence.
terus is very conversational (“and then/so”). Example: Setelah rapat, kami jalan-jalan sebentar, lalu/terus ketawa bersama.

Should I use sambil to show the actions happened at the same time?

Use sambil to stress simultaneity:

Setelah rapat, kami jalan-jalan sambil ketawa. This reads as “we were walking around while laughing,” clearly simultaneous. With dan, they can be sequential or loosely overlapping.

What’s the nuance difference between bersama, bersama-sama, and bareng?

bersama: neutral “together/with.”
bersama-sama: emphasizes “all together/as a group.”
bareng: colloquial “together/with.” Examples: ketawa bersama (neutral), ketawa bersama-sama (emphasis), ketawa bareng (casual).

Is rapat a noun or a verb here?

Here it functions as a noun (“meeting”). But rapat can also be used as a verb in context: Kami sedang rapat (“We’re in a meeting right now”). Note: rapat also means “tight/compact” as an adjective in other contexts.

Can I drop the subject kami?

In everyday sentences, keep it for clarity. Omitting it (Setelah rapat, jalan-jalan sebentar…) sounds like a note or diary fragment and can be unclear in conversation.

Is bersama dengan okay, or is dengan redundant?

Both bersama and bersama dengan are acceptable; dengan adds formality and is common in official writing. With verbs like “ketawa,” you’ll more often see simply bersama: ketawa bersama.

Any more formal and more casual rewrites?

More formal: Setelah rapat, kami berjalan-jalan sebentar dan tertawa bersama.
More casual: Habis rapat, kami jalan-jalan bentar terus ketawa bareng.
Inclusive casual: Abis rapat, kita jalan-jalan bentar terus ketawa bareng. (only if the listener was part of “we”)

Pronunciation tips?

Setelah: se-TE-lah (the “t” is unaspirated).
rapat: RA-pat (final “t” is a clean /t/).
kami: KA-mi.
jalan-jalan: JA-lan JA-lan (both parts stressed evenly).
sebentar: se-BEN-tar (short “e”).
ketawa: ke-TA-wa (open “a” sounds).