@Unoptanio per the upgrade guide
https://docs.netgate.com/pfsense/en/latest/install/upgrade-guide-prepare.html#packages
“The safest practice is to remove all packages before upgrading to a new release. The upgrade process will handle packages automatically, but packages are frequently a source of problems. To ensure a smooth upgrade, note the installed packages, remove them, perform the upgrade, and then reinstall when the upgrade is complete.”
No it’s not required. pfSense will upgrade packages.
Yes the package setting remain in the configuration file by default.