Just an update for anyone new to Qubes-Whonix who would like to preserve all the different sets of bookmarks etc. that they have painstakingly implanted into various custom AppVMs of their own design … once.
The AppVMs that I originally created on a system installed on the internal HDD can be backed up and restored onto a new system on an external USB drive, and as I discovered yesterday, they even work on a USB stick too.
It seems that the virtual machines created in Qubes are independent of the hardware from what I can gather. Sometimes, some of them seem to take a long time to shutdown, and after 2x20 seconds I have been inclined to kill them, but I am about 66% sure that it is because they are large VMs with a lot of applications installed. I wish I could go back and test how fast they shutdown on hardware with an internal HDD, but now that I have Qubes and Whonix running fine on both the external HDD and the USB stick, I have restored the internal HDD OS to a plain and simple Linux distro with nothing on it, (the SSD is almost 2 years old now so I don’t trust it anyway).
In essence, the several AppVMs I created last week on the laptop have been backed up and then restored multiple times to the external HDD (USB) and also to a 64GB USB stick and work just fine. No need to reconfigure all your preferred AppVMs every time you reinstall Qubes, which would also apply to Qubes-Whonix.
I hope that this can save others some time in experimenting with Qubes-Whonix because it is not necessary, as far as I have found, to recreate the same AppVMs over and over again each time you try a new installation.