Sounds like a fun update. The stairs thing looks fun to play around with, and the family additions will be great for storytelling.
I'm very excited the the hair tag overhaul. Glad to see the Afro-Textured category is back. But it'll finally be able to find regular curly hair or specifically afro-textured hair. Having both of them lumped together in one category made it hard to find what I want for my sims. So this is a big quality of life change for me.
EDIT:
It keeps the data about dead sims even after they get purged from the save
AAAAAAAAAAAAAAAAAAH so looking at the code changes, it looks like the game will keep sims on the genealogy panel even after they've been long dead? I had a mod to prevent ghosts from fading, solely because I didn't want to have a bunch of blank spots on my tree. And that couldn't be good for my game, having dozens of dead sims hidden away. If this keeps them on the tree, then this is fantastic news for me.