GPIB with C# - 64\32 bit OS issues

We use some NI devices and we build a .NET application (C#) that needs to communicate with the devices through GPIB.

The application have two versions one for windows 32 bit (XP) and one for 64 bit (Win7) (The 64 bit application cannot be compiled as x86 because of other reasons).

As I have seen in NI examples we need to use NationalInstruments.Common.dll and NationalInstruments.NI4882.dll in order to communicate with the devices.

I have some questions about using it.

1. Are there NationalInstruments.Common.dll and NationalInstruments.NI4882.dll for 32 and 64 bits or they have compiled as AnyCpu?
2. Which drivers should be installed in order to use the above dlls? There are versions for 32 bit and for 64 bit OS?
3. If on one computer (64 bit) one of those drivers already installed in a 32 bit version (because other 32 bit applications need it) is it disturb?

Thanks