please forgive me, but I am having a good old laugh here, as once again I did not stick to my intuition. Earlier on I did pick up that there seemed to be and odd description of changing drivers.
Start FireFox > Print > General
Do you not see the 3 printers you have just sent me details of? Well you should as I have just checked on and LXDE system, using Firefox and I see the two NX200 and TX200 that I have installed in a rush.
To switch 'driver' or 'printer' or 'printer que' is a better description but I have a nagging feeling that in general the que term is not understood, but what does it matter if the system works.
Here you select your printer and then set up the parameters needed.
This I believe will be standard for Adobe Acrobat, OOo Thunderbird ... almost any application. You ought to be able to to switch to any printer you have installed from within any application.
You also ought to be able to install any printer you don't physically have, this is how I have 3 of your printer drivers and 3 other printers installed here on this MiniMe system and on my workhorse KDE I have had about 18 at one time, and only two of thos did I have a physical printer for.
(Note: I have not made any mention on how I install the printers)
Naturally I am unable to do the very last step in the administration, ie print to paper, using any driver which does not physically have a printer attached.
Ok, can you confirm the FireFox step?