Drivers are basically the software for the sound card that makes it work. You simply need to make sure the drivers for your chosen sound card will work with your operating system.
The cables are easy to source and fairly cheap unless you want to spend more on better quality cables. If you need to know which cables you need then just ask.
With SPL meters, I know the RS analogue meter has a correction file to correct for its inaccuracies, but I dont think it covers the digital one, perhaps someone else can confirm this. If you want a more accurate meter in general it will cost more. As long as your happy to spend more then thats fine, just make sure your chosen meter is a 'C' weighted one. If you would like pointing in the direction of a good mic then just ask :T