I regret having to disappoint you but I'm no expert. Similar threads here seem to have received little response and you may be better off posting in the Mozilla forum
If you mean that Firefox fails to launch, that could be because the shortcut you are using does not have the correct path or because you do not have permission to execute the file. No doubt there are other possible explanations and neither of those seems likely.
If you know how to open a terminal or console, you could try launching Firefox with a command line. The simplest way is to type the full path, for example, /usr/bin/firefox. If Knoppix will allow that, you should get feedback which explains what happens.
On the printing issue, you may get some help from this page: http://kb.mozillazine.org/PostScript_Module
Firefox issues generally: http://kb.mozillazine.org/Category:Firefox
In your shoes, I would look for some general information about Knoppix in particular and Linux in general as it seems as though that's what you need. As always, there are many useful links in DistroWatch: http://distrowatch.com/table.php?distribution=knoppix