Welcome back to Subeta! Sorry to hear about your pet names, but keep in mind you should have a free name change waiting on those pets (you will see the price is 0 CSC when you go to change names on those pets).
Let's try to tackle your questions:
The little check boxes allow you to 'save' achievements that you might be working on or something for easy reference under the 'Saved' area too.
I believe you can file a ticket to get your current skin unlocked in the wardrobe, I'm pretty sure that's what I did to redeem my old skin. Any prior skins you have had before this one will not count, but you can re-earn them during site events such as Morostide or the great Pandemic. Some are also unlocked via achievements, or other site events :)
It's hard to pinpoint what's different about the economy, I guess certainly CSC costs more than it used to, and I think sP is a little easier to earn (especially with questing). Was there anything particular you had in mind?
Lots of changes and events, I guess site events now follow a schedule so it's easier to reference (see Subetapedia, under Subeta on the top nav bar), and shops are currently going through a revamp to help control lag on the site (there's lots to read up in the news post, it's just been fully live for about half a day)
I think you are correct that the forum topic creation isn't working, I'll have to skim through the Problems and Bugs to see if it's a known issue.
Let me know if that helps a little, and if there's anything else I can answer :D
Useful Links:
What to do on Subeta? Useful general information for newbies Finding friends (Chit Chat) SubetaLodge (Offsite item database, pet colours etc.)
FAQ Upcoming event: Vesnali (Scheduled last week of April)
2025 Stalacbite, Focused (7)