4. What you are trying to do is clear cookies and history regularly so trackers can't vacuum that data up. You can probably set similar defaults in Safari but I don't know how.
5. I advocate for Firefox because they have protections against browser's fingerprinting. I don't know if Safari has these, you would have to check.
6. You should use encrypted chat, it doesn't really matter which you choose.
This is a pretty great video which walks through everything I just said and more in 15 minutes: https://m.youtube.com/watch?v=gFsRXfifcYg
