Issues during installation Arch - couldn't boot with UEFI motherboard

I followed strictly to the Arch Wiki 'Beginners' guide'. As I'm using a new computer, and the motherboard support UEFI mode, I tried this new mode for the first time, and get some issue.

I don't know what does the 'EFI system partition' mean, so I made such a partition, plus an additional boot partition. After completing the procedure provided by the wiki, I found that the 'EFI system partition' is itself a boot partition, I don't need an additional boot partition. Then I deleted the boot partiton and merged the disk space into that EFI system partition. When this was done, with other procedure completed, I rebooted the system. But the system complains that "Error reading \vmlinuz-linux.img: Not Found". Oops, that's because the .img file located in /boot was deleted with the original partition. So I rebooted the system with the installation USB disk, reinstall the package "linux", and the .img file is back!

But after I rebooted the system again, it complains that /sbin/init couldn't be found. Well, this is because I made /usr folder an explicit partition, it need and hook 'usr' for the kernel. Reboot the computer with installation USB disk again, modify /etc/mkinitcpio.conf, add 'usr'(without quotes) into this line:

HOOKS="base udev autodetect modconf block filesystems usr keyboard fsck"

then run 'mkinitcpio -p linux' again, this will fix that issue.