I think you'll find its not Firefox that is the problem, but the Google Toolbar
That has all kinds of stability issues - and I expect that the version you have is out of date. You're better off without it - remember the only reason it exists is to make it easier for Google to hijack your data. As a general rule, you are better off without toolbars. If you really want it, go to the Google website and download a newer version
To the specific question regarding uninstalling / reinstalling Firefox- just uninstall in the usual way from add/rem programs, or programs & settings depending on version. If you try using Final Uninstaller you'll probably find the Firefix profile will be lost and any Firefox favourites will be lost. Having said that, my personal view is that Final Uninstaller breaks more than it resolves: the only one of the brute force uninstallers I've found that I'm happy with has been Revo Uninstaller Pro (use the 30 day trial as/when needed)
Regarding the question re the shortcuts - are these the Firefox shortcuts, or the Google shortcuts?
As to Firefox V3.6 -thats inherently insecure and the newest Java / Flash and other plugins probably won't work in it