New Traits

Carl's got a good trait guide on his website:
https://www.carls-sims-4-guide.com/traits/
You can see what the traits do and what packs they come with. :)

Sure! There are:

Get Together: Dance Machine, Insider (club-related)
Cats & Dogs: Cat Lover, Dog Lover
Get Famous: Self-Absorbed
Island Living: Child of the Islands (based around Sulani traditions), Child of the Ocean (most comfortable in the water)
Eco Lifestyle: Maker, Freegan (basically an anti-consumerism one), Green Fiend, Recycle Disciple (will recycle everything. EVERYTHING)

Outdoor Retreat: Squeamish (around bugs, vomiting, violence, death, and dirty things)
Strangerville: Paranoid

The ones I didn't elaborate on are pretty self-explanatory. Cat Lovers like being around cats! Who knew ;)

There are also a few bonus traits for pack-based aspirations - the Friend of the Animals aspiration from C&D gives the Animal Affection trait (relationships with animals start higher), and City Living, Strangerville, and Island Living all have location-based aspirations that give the Home Turf trait (Sims are happy when in their neighbourhood).

@Camkat Thank you for the guide! :)

@ryttu3k Thanks you :) Its nice to see which traits come with which expansion pack, but I dont think they all have traits included do they?? I wish that they all did.