CD is not supported.
The BIOS options regarding booting and USB configuration you need to test yourself, there are too many different around.
Some common advice are:
- Different USB ports tried?
- Does the stick boot on other PCs?
- Is the latest BIOS installed?
- Default BIOS setting tried?
Does it work if if you replace Requires= with Wants=?
There is a failing storage-ServerFolders.mount ( milhouse different unit name):
Dec 31 16:00:28 le-mx3 systemd[1]: storage-ServerFolders.mount: Directory /storage/ServerFolders to mount over is not empty, mounting anyway.
Dec 31 16:00:28 le-mx3 systemd[1]: Mounting cifs mount script...
Dec 31 16:00:28 le-mx3 connmand[3297]: eth0 {add} route 212.227.81.55 gw 192.168.1.1 scope 0 <UNIVERSE>
Dec 31 16:00:28 le-mx3 kernel: FS-Cache: Netfs 'cifs' registered for caching
Dec 31 16:00:29 le-mx3 connmand[3297]: ntp: adjust (jump): +96438127.610211 sec
Jan 20 20:22:36 le-mx3 systemd[1]: Time has been changed
Jan 20 20:22:36 le-mx3 connmand[3297]: eth0 {del} route 212.227.81.55 gw 192.168.1.1 scope 0 <UNIVERSE>
Jan 20 20:22:37 le-mx3 connmand[3297]: ntp: adjust (slew): -0.006555 sec
Jan 20 20:22:42 le-mx3 systemd[1]: storage-ServerFolders.mount: Mount process exited, code=exited status=255
Jan 20 20:22:42 le-mx3 systemd[1]: Failed to mount cifs mount script.storage-ServerFolders-Videos.mount is getting an automatic dependency to storage-ServerFolders.mount and cannot started because of the failure.
Assuming you do not need/want storage-ServerFolders.mount any more just disable or delete it.
Anything in systemctl list-dependencies storage-ServerFolders-Videos.mount?
systemd supportsRequiresMountsFor=/path/.. in [Unit] section.
These modifications are only needed to disable a real power button like the case power switch.
Most remotes do not have the feature, then the <power> key is mapped to Shutdown() in the Kodi keymap.
You can try some additional logging. Boot without USB drives and log into ssh. Type:
udevadm monitor >udev.txt
Attach a failing drive and press <Ctrl>-c after a short time. Then:
journalctl >journal.txt
Post the two files.
But there is no guarantee that there are any findings.
1) What type of network (WLAN, ethernet, ...) are you using?
2) Did you try this:
if so pls force a refresh of the repos -> go to addons -> Download -> left side panel -> check for update
Remember when you moved your cable from HDM1 to HDMI2. 
More serious: remove all EDID kernel parameters to start with auto detection again.
One final thought: did you check if one of the graphics cards can be forced in the BIOS options?
At a guess:
cp /lib/udev/rules.d/97-xorg.rules /storage/.config/udev.rules.d/In the copied file remove the line starting with DRIVER=="i915", and reboot.
Which videos do not play?
I'm still testing on my AMD C-60 netbook with HD 6250 and it woks up to 1080p/1080i h.264.
Free space check is done here.
To i.e. check if your large drive is detected correctly open python and type:
import os
s=os.statvfs('/var/media/xstorage')
s
s.f_bsize*s.f_bavail/boot/grub/custom.cfg can be used instead of (or in combination with) /etc/grub.d/40_custom with the advantage no update-grub is needed after editing.
update-grub
Oh, yes. Forgot that's not common to use /boot/grub/custom.cfg
lost+found is normal for ext? file systems and may be created even without error.
LE_SYSTEM can be even formatted FAT32, only LE_DATA needs ext4.
I mounted the LE_SYSTEM partition in Ububtu [...]
That is really odd. You can try the same with grub console. On the grub boot menu press 'c' to open the console. Then:
ls -l (hd0,5)/I have no experiences with rEFInd but in general you have to pass 'boot=LABEL=LE_SYSTEM disk=LABEL=LE_DATA quiet nosplash' as parameters when booting the KERNEL file.
The "ext2" module supports ext2, ext3 and ext4.
error: file `/KERNEL' not found.
Most likely the kernel file is not named "KERNEL". Please keep in mind that ext4 is case sensitive.