I'm doing a series of installs to find an optimum configuration
for my personal needs.
OK, this is important. Great goal by the way! :)
As I DO NOT have high speed internet available I have purchased a
set of Squeeze DVD's.
Great. Wheezy might have been better, but squeeze may be better if
your hardware is older; may be, may be not; the Linux kernel has
pretty stellar backward compatibility, at least within a few
generations.
My impression is that I should be able to copy the set of DVD's
to a flash drive and access as loop device to save physically
handling DVD's when using apt-get etc.
Here's where the XY problem may be coming in. Yes you can create an
image easily of a DVD or CD, with the following being just one of many
ways to achieve that:
sudo readom dev=/dev/scd0 f=my-image.iso
BUT, if you want to experiment with different desktops, settings,
kernels etc, in the Debian world, then here's what I suggest:
First key point: I sent a few emails to your earlier threads, the
primary one of interest is about how to create a local repository of
Debian packages. Your USB stick might as well contain a local archive
of the packages on your DVDs, no point going through the rigmarole of
having to mount each ISO image each time you plug in the stick
(although admittedly you _could_ script that to automate it).
The second key point is that you will most likely _still use_ your
first DVD, for installation purposes, even to do a minimal install;
and a Minimal Install, using "Advanced" installation option from the
DVD, is definitely what you want! :)
because thereafter, you install just those packages you want to learn
about. Et voi la! The magic of an awesome and essentially unlimited
learning curve of inspiring free/libre software.
Note: Your process is really quite similar to my own process many
years ago. I did even learn (briefly) (at one point many years ago),
how to get the grug (or perhaps lilo back then) to boot up a CD/DVD
image sitting somewhere on the HDD. I never really used that though,
except you could use it to install into a _secondary/learning_
partition, whilst still having a "current stable" partition, but since
you have a dedicated PC for your journeys here, this is not necessary
for you at all.
Here is a link to my earlier email on this list. Again, I strongly
suggest you create a local package pool (on your USB stick) using
those instructions, and then add that (using a "deb file:///..." type
line) in your /etc/apt/sources.list file, each time you do a new
installation for some new tests:
https://lists.debian.org/debian-user/2013/11/msg00374.html
As you can see from that link, your follow up message showed that this
procedure worked for you.