Soon(TM).
Yes. The release announcement for the 5.0 beta has the upgrade commands. When the master 5.0 is released, you would shift from beta 5.0 to master with pihole checkout master
Please note the large disclaimer on the release notice - the upgrade is one-way only. Make a backup of your SD card so you can revert to 4.X if desired.
https://pi-hole.net/2020/01/19/announcing-a-beta-test-of-pi-hole-5-0/#page-content