On the Atlas screen, there's a new Kirac's Vault Pass icon at the top left. Clicking that will let you buy the pass, see the rewards and travel to Kirac's Vault.

The Pass has a progress bar that tracks how many bonus objectives of maps on the atlas you have completed. Once you have unlocked a reward, you can click a button on the Pass screen to travel directly to Kirac's Vault, where a chamber containing that reward will unlock for you to claim.

Once claimed, items are dropped on the ground, while the cosmetics are stored in your microtransaction stash, alongside your existing microtransactions.

You're now able to buy it using 300 points, rather than $30 cash. Note that spending $30 on a supporter pack gets you 300 points, so for the same cost of the Kirac's Vault Pass, you're now able to receive an entire supporter pack as well as the Kirac's Vault Pass and its contents.

No. Access to Kirac's Vault and its cosmetic skins offer no gameplay advantage over other players. Items from the free track are available to all players regardless of what they've paid.

No. The Pass costs the same amount regardless of how many objectives you have already completed, and the relevant rewards will unlock instantly if you buy the Pass after completing objectives. There's no penalty for delaying your purchase until later in the league, though you'll need to purchase it before the league ends.

You can't pay to unlock rewards. Everyone you see with one of the exclusive skins from Kirac's Vault will have completed the bonus objectives required to earn it.

No. At this stage it is only available to players in the current challenge league because many Standard players can instantly unlock their whole Atlas by completing a single map.

Yes. Any cosmetics earned during this league will be available account-wide and can be equipped to any character you make in any league.

The Archon of the Atlas Armour Set won't be immediately available for use in Path of Exile 2, but will be added in the future.

No. The Pass can only be purchased during this league and its cosmetic skins are exclusive to this Pass. They will not be available again. If you want to have them in your collection forever, you must purchase the Pass this league and complete the objectives for any skins that you want.

The pass tracks your highest Atlas progress from any Mercenaries league you are playing in (including private leagues based on Mercenaries).

Absolutely.