- Apr 30, 2020
- Gigabyte Z490 Vision D
- RX 6800 XT
- Mobile Phone
Yes it's possible to use an ordinary HDD if you're okay with the slower speed.
Sure, this is also perfectly viable. Both partitions and APFS volumes can be used. APFS volumes are described in Tech Talk in Post 1.
I would recommend not to store important backups on the same physical disc though ... If you have another backup (like Time Machine) and this is just a safety measure for problems with macOS updates etc., it might be ok.