Thanks for the ideas. I've been trying them out.
John, I have experimented with the ACPI and ACP settings in the BIOS now. Nothing worked until I updated the kernel as suggested by Paul for the USB problem. Now if I have APM turned on and set ACPI to S3 instead of S1 the computer will suspend to RAM using your command as root (but not from the logout screen). Trouble is, when I press the power button to wake it up I can hear the hard drive and the fan run, but the screen stays off. I eventually have to shut down with the power button. So, some progress, but not a complete solution yet!
Paul, I installed kernel version 18.104.22.168 and modules, and as you read above it helped with suspend to RAM but not - unfortunately - with the disappearing USB folder. But thanks for the suggestion anyway, I would probably never have got around to trying to install a new kernel if you hadn't suggested it! And thanks to Uelsk8s and stretchedthin for the excellent howto and video tutorial.
Any more ideas welcome.