It is not silly. It is that you haven't done the basic homework, while you decided to go with a rolling release distro. But don't worry, you are not the first that does that. Here:
How to provide information about your issues
How to change video drivers or configuration and troubleshoot section Log your troubleshooting info in a file
Not the booting messages, of course, but in TTY (after logging in to the "black screen").
From Archwiki on
<fsck>sets the order for filesystem checks at boot time; see fsck(8). For the root device it should be
1. For other partitions it should be
0to disable checking
Meaning, the partition is still checked on boot. You disabled it with
0 and it went on, so it seems there is possible a drive error.
This is from the package installation process and is not fatal. Have you completed Gsmartcontrol installation? Do it and check the drive.
systemd was downgraded in Testing. So, you are a Tester!?? Nice!..
In "Advanced options for..." submenu, options with "(fallback)".
Now you see why it is a good practice to use a separate partition for your home, unless you ask only for a different disk.
If the target partition is ext4, even copying the users folders (including hidden files) should be enough. Rsync is a good choice, if you can use it for the job.
As it is a brand new installation, yes. Unless you have made several system files changes (grub, Xorg etc) then you should backup
/etc as well. I would also backup (and re-use) downloaded packages (
/var/cache/pacman/pkg), but you're not me .
I hope you fix your drive and hopefully the errors.