Question

do you know any other expressions you can use when you say hello and goodbye?

Answer 1

Hello = Hey, Hey whats up
Goodbye = See ya, Bye bye, See you later

Answer 2

Expressões para cumprimentar (dizer olá): Hey, Hi, Good Morning, Good Afternoon, What's up?, How's it doing?
Para se despedir: See you later/soon, Bye, See you next time, Take care, Have a nice day.