1) You can check in device manager. Right click on each device and in properties check driver details and location. Alternatively, use something like double driver (freeware) to backup installed drivers. Double driver will clearly show all installed drivers, both MS and 3rd party.
2) To update drivers, you can either use windows update/device manager or use a 3rd party tool like driver magician or manually navigate to the manufacturer's website and download the latest drivers. The last method is recommended since the first two can throw up obsolete drivers or not show a new driver because it dosnt exist in their respective database.
3) Installing a new driver will automatically supersede the older one. You can also remove old drivers yourself.
Guru3D - Driver Sweeper
Uninstall Drivers from Vista & Windows 7