I VERY MUCH appreciate the quick response info. Rather than write separate answers I've put all into one combination, which will include progress I've made in the past couple of days. First, in Re -- some requested clarifications --
* My new Mac has an Intel, not M1, processor and yes, it's the one running Big Sur.
* Fusion 12 was successfully used for the installation on the new Mac. It works (e.g., I get the basic "My Computer" screen when I start vmware, which now has a ramdisk I just put in). VMware tools is also present.
* The installation was done with a Bundle. Although I provided the installer with a full set of files from the old Mac, the installation for some reason was bare-bones (e.g. -- 0 bytes in autoexec.bat; 0 bytes in config.sys -- which I changed to put the ramdisk in; most application programs missing, etc.).
* That might be OK; the old Mac has outdated stuff. I can give the new Mac a clean C: drive. Another reason is I've let the two Macs diverge; each may have a few things not on the other.
* I haven't yet succeeded in getting file sharing to work. That's mainly where I need help; from "My Computer" I don't see any command to map a network drive (or should that be done from the Mac side?).
* Since my Windows work consists of a small number of functions, I'd like to proceed thus: First, get file sharing to work. Then connect a folder I can use as a scratch-pad I'll copy to from the old Mac's documents and programs (e.g., whole folders under C:\Program Files --
if that's too laborious I can just copy the entire C:\Progra~1 folder; it will easily fit). I'd also copy whole folders under C:\Matlab, C:\Office, chosen parts under C:\Windows, etc.
It will take some work but, unless there's something fundamentally wrong with this plan, I can get through it. Again, I'm very grateful for the responses received.