sorry
Windows loader should be auto detected, by default on arch the timeout is commented out though, so he might need to enable that
Easy fix; you probably didn't mount your ESP to the correct place (/boot is default for Gummiboot), or didn't mount it at all, and therefore, your fstab doesn't know where it is. When booting, it is pointing to somewhere that doesn't exist to it. To fix it, mount your /boot, /, and whatever other partitions you have, then chroot into /, delete your fstab, genfstab, and reinstall the kernel.