New user seeking advice for privacy

Hello! I'm making the switch to Graphene as a first time user. While I know that my questions have been covered previously I thought it might make a good refresher for other noobs, and a nice thread compiling the updated information.

Upon switching to graphene I have several apps that I use regularly and am looking for alternative secure options, or to learn how others utilize these apps still (sandbox, web browser, etc.)

1. Gmail for business email
2. Instagram
3. Reddit
4. Maps
5. Password manager
6. Amazon
7. Ebay

Lastly, I see everyone has become partial to Firefox for a browser. I've used brave for the past year. Any particular reason to switch?

Thank you kindly in advance.