Cannot boot Arch (USB or HDD) in UEFI Mode

Question

I have a new MSi GT70-0ND, 1x 128GB SSD (no RAID) and 1x 750GB HDD. The SSD was preloaded with an MSi OEM copy of Windows 8. I did not receive an OEM disc, so I've tried to avoid touching the SSD and the hidden recovery partition on the HDD.
Using Universal USB Installer, installed archiso onto USB flashdrive.
Windows boot device selection menu did not detect the flashdrive.
Checked UEFI BIOS settings - USB set to "Full Initial".
Moved flashdrive from port to port, eventually was detected.
Reboot, received an error relating to bootloader signing.
Rebooted again into UEFI BIOS settings, disabled secure boot.
Rebooted, received infamous "No loader found. Configuration files in \loader\entries\*.conf are needed."
Googled, checked forums, saw gummiboot issues, recommendations to use rEFInd, and dd/UEFI issue.
Transferred archiso to working Arch machine, followed instructions here https://wiki.archlinux.org/index.php/UE … B_from_ISO.
Installed rEFInd using instructions here https://bugs.archlinux.org/task/31894#comment102233. I have since tried various changes to refind.conf and can not discern any difference.
Attempted to boot laptop from flashdrive in UEFI mode after Windows' boot device menu again failed to detect flashdrive multiple times.
Got rEFInd menu, found nothing functional (except Windows bootloader, of course): Arch entry froze the system requiring hard reboot, UEFI Shell v2 gave an assertion error (from memory, it was "String.c(166) String != ((void *)0)"); Googled, seeing some related but no identical errors, UEFI Shell v1 failed to start reporting something like "using load options '<null string>'".
Rebooted in BIOS/Legacy mode, but flashdrive was unbootable (duh)
Again using Universal USB Installer, installed archiso onto flashdrive.
Rebooted in BIOS/Legacy mode, archiso menu appeared, but during udev events, received a drm/nouveau init table error; Hard reboot. Appended
nouveau.modeset=0
to kernel line, everything worked
Installed vanilla Arch system to the HDD including UEFISYS partition.
When it came time to set up and install rEFInd/efibootmgr, of course
modprobe efivars
failed.
Redid flashdrive the UEFI-safe way on Arch machine, attempted to boot in UEFI mode, it appears that menu entries from my /boot/efi (UEFISYS) partition are present, but this is irrelevant as only the Windows bootloader and \refindx64.efi work (loads rEFInd graphical mode, in which nothing works except BOOTX64.efi which quickly flashes a message with a file path (too quickly to read) then loads Windows. UEFI Shell v2 now has same error as v1:
Using load options '<null string'> Error: Not Found while loading shellx64_v2.efi
rEFInd (version 0.5.0) "About" dialog reports EFI Revision 2.31, Firmware: American Megatrends 4.653, Screen Output: Graphics Output (UEFI)
I have tried adding various things to the refind.conf "options" directive, e.g. gpt, loglevel=7, pci=nocrs, add_efi_memmap, archisobasedir=arch, archisolabel=ARCH_201212, acpi=off, etc. in different combinations.
I am at wits' end. Bottom line: nothing but rEFInd (via flashdrive) and Windows works in UEFI boot mode - nothing. Any help will be greatly appreciated. Thank you.

Answer 1

I doubt if this will help you with your main goal, but I've fixed a few memory bugs in rEFInd recently, so the "String.c(166) String != ((void *)0)" error you mentioned might go away if you upgraded to the latest version of rEFInd (0.6.0).
Beyond that, here's a suggestion:
Prepare a USB flash drive or CD-R with rEFInd 0.6.0. Be sure to include an EFI driver for whatever filesystem you used in Arch's /boot (or root, if there's no separate /boot partition) in the flash drive's or CD's EFI/BOOT/drivers_x64 directory. (Note that rEFInd 0.6.0 includes an ext4fs driver.)
Using an emergency disc, create a refind_linux.conf file in Arch's /boot directory. Include, at a minimum, two lines, each of which should include the options "ro root=/dev/{whatever} initrd={\path\to\initrd}", changing the device filename to point to your root and the initrd= specification to point to your two Arch initrd files (one for each line). The path should be relative to the root of whatever filesystem holds those files, so if you've got a separate /boot partition, there would be no directories, just the filename preceded by a backslash; and if you have no separate /boot partition, you'd lead with "\boot\". Note the need for BACKslashes, not forward slashes, in the initrd= specification (but forward slashes in the root= specification).
Reboot using the rEFInd flash drive or CD-R you've prepared. With any luck, rEFInd should come up and show you an Arch option. Try using it. If it fails, try again, but hit Insert and select the second option from the list.
With any luck this will get your system booted in EFI mode, but I can't make any promises about that.