The first place you'll most probably want to look at is the Print & Scan option within System Preferences. There you'll see a list of all printers that you have installed. You can optionally uninstall each of them by clicking on the minus '-' at the bottom of the list.
Also, if you are troubleshooting printer issues, you might want to try right-clicking within the list and select Reset printing system. Apple has a document about what resetting the printing system does here: http://support.apple.com/kb/HT1341
On your question about where the drivers are actually installed, the answer would be in the /Library/Printers folder. I've noticed some printer drivers were left intact in this folder even after I uninstalled them. I've removed some of the files here myself and would say that it is generally safe to do so. However, I'd still suggest that you uninstall your printer drivers from within Print & Scan first before traversing into this folder.