Feel free to move the topic to the other forum!
Essentially, I have next to no options remaining that I can think of. I tried resetting CMOS this morning; interestingly now my Windows repair disc actually boots, but it still can't see the hard drive/Windows installation. I tried running in safe mode again (which happened to be while the disc was still in), and it went straight to System Recovery Options (with the same results above), just with 'Safe Mode' appearing in each corner of the screen as well. I have yet to test a couple more combinations of those kind of things after the CMOS reset (like your rescue usb, and safe mode without a repair disc in), not that it's likely to be revolutionary. When in System Recovery, I also tried the Memory Diagnostic ("Windows cannot check for memory problems; An error is preventing Windows from checking for memory problems during startup") and moving through the system image dialog, at one point received the error "This service cannot be started in Safe Mode (0x8007043C)", an error which appears to be associated with Windows Update, for some reason. Again, nothing revolutionary.
I agree that the Toshiba recovery tools may very well not work, in which case I imagine I would try to wipe the drive using Ubuntu, test it with Ubuntu or SeaTools for DOS, and then install Windows again, assuming it works?
Guides to non-booting computers, as well as several of the error messages I've seen, also mention fixing loose HDD cables/reseating connections as an option... working on the interior of a laptop is not something I've done before (and I imagine is more fiddly than a tower), but unplugging and plugging things in can't be that bad as a last option prior to trying to factory reset/wipe... can it? I'll hold off for now.
That said, if anything else doesn't work, I will need to try the reset/wipe soon, because I am currently staying with my family where I have access to another clean computer- tomorrow I'll be going home where I won't have easy access to another computer, and this will all become more difficult.