Learn Hardcore Turkish: Toplantı ilanı az önce yayımlandı, ben onu kaydedip paylaştım. - The meeting announcement was just published; I saved it and shared it.

Here -ı is not accusative; it’s the 3rd person possessive suffix used in an indefinite noun compound. Toplantı ilanı is an indefinite compound meaning meeting announcement, where the head noun (ilan) takes -ı/i/u/ü. Accusative -(y)ı/i/u/ü looks the same on the surface, but it marks a definite direct object, e.g., ilanı kaydettim = I saved the announcement. In your sentence, toplantı ilanı is the subject of yayımlandı, so that -ı is possessive.

What’s the difference between toplantı ilanı and toplantının ilanı?

toplantı ilanı: an indefinite compound (type-of relationship). Natural way to say meeting announcement. It can still refer to a specific one from context.
toplantının ilanı: a definite genitive compound (possessor + possessed). It explicitly says the announcement of the meeting, with more emphasis on that particular meeting.

Both are possible; the first is lighter and very common in titles or headlines.

Why use the passive yayımlandı? Could I say an active form like ... yayımladılar?

Turkish news style prefers the passive when the agent is unknown, irrelevant, or obvious from context: yayımlandı = it was published. You can use an active form if you name the agent, e.g., Belediye ilanı yayımladı. Using an unspecified -dılar (they) is possible (... yayımladılar) but is more colloquial and still leaves the agent vague.

Is there any difference between yayımlandı and yayınlandı?

Both are widely used and understood. Traditional advice: use yayımlamak for publishing print/online texts and yayınlamak for broadcasting (TV/radio). In everyday usage the distinction is often ignored, so yayımlandı and yayınlandı both occur with little practical difference.

Can I say az önce yayımlanmış instead of az önce yayımlandı? What’s the nuance?

yayımlandı (simple past -dı): neutral, you present it as a known fact, often because you witnessed or are asserting it.
yayımlanmış (evidential -miş): inferential/hearsay nuance. It suggests you learned or inferred that it was just published (e.g., you’ve just discovered it).

Both work with az önce, but -mış changes the evidential flavor.

Can I use henüz instead of az önce?

Prefer az önce for just now. Henüz usually means yet and pairs best with negatives: henüz yayımlanmadı = it hasn’t been published yet. Some speakers use positive henüz yayımlandı to mean just now, but it sounds nonstandard or regional; stick to az önce or yeni in neutral Turkish.

How does the -ip in kaydedip work? Does it just mean and?

-(y)ip is a converb that links verbs sharing the same subject (and usually time frame). Only the last verb in the chain carries tense/person/negation:

(Ben) onu kaydedip paylaştım = I saved it and (then) shared it. It often implies sequence. You can chain more than two verbs the same way.

Does onu serve as the object for both kaydedip and paylaştım? Do I need to repeat it?

Yes, onu scopes over both verbs. You don’t need to repeat it. Onu kaydedip onu paylaştım is grammatical but stylistically odd unless you’re adding strong emphasis.

Where can I place onu? Is kaydedip onu paylaştım okay?

Neutral placement is before the verb cluster: Onu kaydedip paylaştım. You can say kaydedip onu paylaştım to put focus on the object in the second action (I shared that one), but it’s a marked word order. Placing onu after the whole cluster (kaydedip paylaştım onu) is possible in speech for emphasis, but not the default.

Do I need ben? Could I drop it?

You can drop it: Onu kaydedip paylaştım. Turkish is pro‑drop, and the -m in paylaştım already shows first person. Keeping ben adds emphasis or contrast (I, as opposed to someone else).

Why is it kaydedip with d, not kaydetip?

Because kaydetmek is a compound verb (kayıt + etmek) and the t of et often voices to d before a vowel. With -ip, this yields kaydedip. Similar patterns:

reddetmek → reddedip
hissetmek → hissedip
zannetmek → zannedip

Could I connect the two main clauses with ve instead of a comma?

Yes: Toplantı ilanı az önce yayımlandı ve ben onu kaydedip paylaştım. In Turkish you usually don’t put a comma before ve. A semicolon is also fine for two independent clauses: ... yayımlandı; ben onu ...

Does kaydedip paylaştım imply a sequence?

Usually yes: saved, then shared. -(y)ip often carries that sequential feel, unless context suggests simultaneity or manner.

How do I say I saved it but didn’t share it vs. I didn’t save it but I shared it using -ip?

I saved it but didn’t share it: Onu kaydedip paylaşmadım.
I didn’t save it but I shared it: Onu kaydetmeyip paylaştım. Negation on the final verb negates the whole chain; negation on the -ip verb negates only that first action.

Is ilan the best word here? What about duyuru?

Both are fine but have nuances:

ilan: notice/announcement in a more official or formal sense (job ads, official notices).
duyuru: announcement/notice from an organization to inform people. You could say Toplantı duyurusu as well; it’s very common in institutional contexts.