3. Make sure to update your status with SSA. Checkbox on N-400 is ignored.
My fresh experience:
Also register to vote, it can be done online:
https://vote.gov/
@Crazy Cat already mentioned passport.
When applying for passport, I'd personally get large book. It's essentially same passport, just with more pages. This ensures you don't have to renew it as often due to running out of pages. Because it's same price, it was no brainer for me.
Passport card is a nice ID, if you can pay extra. I keep it in my wallet all the time.
a) It's additional proof of US citizenship in case if US passport or certificate is lost
b) It's immediate proof of citizenship for ICE / CBP in current climate that's easier to carry that passport or certificate
c) It doesn't have your address on it! So useful when hotels, hospitals, liquor stores, nightclub bouncers ask you for ID or make copies of it. This gives a bit more privacy.
d) It can be used for land border crossings between US and Canada / Mexico and some cruises.
e) Many states issue DLs / IDs that are valid for 5-8 years. Passport card is valid for 10 years.