Returning player, not sure how to proceed

Hey everyone, I came back to IN after taking a long break (I quit during some falling star/metero shower event) and there is so much new content add I'm a bit overwhelmed.

I take it that Itzaland is the newest addition of the main scenario, and there are a bunch of limited time events focused on that so I should get that done first, but are the Firework Island and the Chinese-inspired region (the one with the painting outift) permanent? Are they part of the main scenario or were they more "sidequests" before the big Itzaland update? I'm also not sure what to do in Sea of Stars, there's a big focus on multiplayer and housing (I've unlocked it, waiting for the vine to grow but that's also been a lot to get through and understand) but there is also a miracle outift and a bunch of upgrades but I have no idea how to get the whimstars, the map region says I've already collected them all.

I have 2 more miracle outifts to craft (second one from the first heart of Infinity, Sea of Star and I'm unlocking Itzaland's), are the non-Itzaland important?

Also do I need friends for the puzzle event in order to send gifts and obtain more pieces? I have the option to request and gift pieces but I can't do anything with that.

Thanks!