What are the default permissions for / and /boot on Arch?
So I've messed up by not formatting my partitions on installation and now things are buggy, dbus returns permission denied on starting is one of the prominent bugs at the moment
Just do the installation again...fixing the permissions maybe easy or extremely hard, depending on how far the problems go. And I don't think you will learn much besides of how the chown command works.
Not with modern package management systems. In the pacutils package is the pacrepairfile tool that is specifically made for repairing file permissions https://man.archlinux.org/man/pacrepairfile.1
I think the point a lot of people are making is that because it's a fresh install it might have been quicker and faster to just reinstall versus whatever kind of checking and troubleshooting you'd have to do with the permissions.
It was only the root of the partitions that I messed up, and I guess the bugs were caused because the Mint live boot only gave the user read permissions (no group or others can read) so I believe shit is fine, plus it's a fresh installation so there's that too