Hello Gordon,
I don't know anything about the situation with the monitor, so I'll leave that aside. But YES, you need to pester the seller to find other bits, which SHOULD have been part of the package. I take it you've not even got system/boot disks?
Regarding the Google thing, I did a quick search basically for what you tried, and the same things came up. I've not tried digging further yet, but I did look up about the ValDocs system, which is a fairly substantial 'desktop' sort of system that may have been supplied with the QX (which was also often supplied with a matching printer - Epson again - which may be important regarding the fancy font support within ValDocs).
The Tech Manual you've seen reference to may be important, and may in fact be the major part of any non-software documentation. There should be further stuff about ValDocs (Valuable Documents). Some articles I've seen suggest the QX was much sold on the back of ValDocs,, and many users could do everything they needed without leaving VD?
Other things I've seen seem to suggest there were 5.25" disk versions of the QX, and also 3.5" versions, hence why I asked about this. The 3.5" version would be DSDD disks, but the 5.25 could be either 40t or 80t but not I think HD. 22DISK supports both. The HX-20/TF-20 system used the same disk format as the 40t QX computers, this leaves about 270k free space after the space reserved for system files. I guess you'd still need to have a 5.25" drive on your PC to use 22DISK, I do not know if the system would run under the 8088 CPU on the QX-16 but it would be a big help if it would.
Most of the docs that you might be looking for would just be generic CP/M systems. The 'problem' with all of this would be the disks rather than the software as such. I.e. getting the software on a disk that your machine can work with. Hopefully you can use something like 22DISK to copy software you can download to a QX-16 format disk. There'll be the problem of finding DSDD floppy disks as well, they're not so easy to find these days?
I use 22DISK quite a lot, doing things re QX disks I've got connected with the HX-20 (although my TF-20 no longer seems to communicate) and regarding my Amstrad PCW which has 5.25" and 3.5" drives attached. I keep at least one old PC operating with floppy disks for this primary purpose.
Way back I was a member of an Epson User Group, regarding the HX-20, but the mag they did ended up having a lot about the QX machines. I didn't take much notice of this back then, I should have a look and see if there's anothing there that might help you.
Geoff