I've read the topic 'can of worms' and see how this is hard work.
I agree with the view that maybe it is best, and easier, to allow change of the user name and password set during installation after 1st boot. I can easily set a default name and password which I can give to each end user. Microsoft get around this in the OEM install by allowing a full installation, install of drivers and applications, and then testing, by the installer. Once testing is finished the 'rollback' facility is called to remove everything the installer has done (apart from the drivers and applications obviously) so that the end user is asked on 1st boot to supply their own log-in name and password. The difference between Windows and Linux is that Linux requires a root password during set-up (making it more secure) but a standard set-up of Windows allows the end user to run as Administrator by default - which is beyond stupid!
Some of them, but not all, will need to install applications themselves. Presently, some, but not all, are receiving assistance via a few Social Services staff who have realised many of these people need such help. The biggest problem for the social services staff who do this is that 1 they really do not have the time, and 2 they have to accept responsibility if something goes wrong with an installation thus requiring them to spend even more time resolving the problem.
I'm no 'expert' but I will be available to answer basic on-line queries.
I have though about using remote log-in facility to provide basic help but this has not yet been discussed with Social Services staff involved, and I'm not sure if it will be allowed anyway.
CPU = U9300, 4GB RAM, Intel GM45 Graphics @ resolution 1366x768, 128GB internal drive, 6TB external storage, Main OS = LMDE Xfce 64bit UP4. 2nd OS = LMDE Xfce 64bit UP4, Other installed OSs = Bodhi 1.4.0, Ubuntu 10.04 & 12.04, Mandriva & Windows.