Hi William,
CR for VS is both 32 and 64 bit runtime now, separate installs. For your DEV PC you install both because you can select either when you compile for a Windows Desktop app or when you set your IIS App Server to run in 64 bit mode.
Short story is VS is a 32 bit app, CR for integration into VS is also running in 32 bit mode, in the VS IDE. For Web app's you set the App pool and distribute the CR runtime to match your app pool setting.
For Desktop app's you set the Project Properties to run in x86 or x64 mode. You have to be specific or the OS and MSIExec will determine what Redist package to use.
For IIS, just set the App Pool to 32 bit mode - True for 32 bit and false for 64 bit.
Remember also, if youa re going to use 64 app pool all of the dependencies must also support 64 applications/app pools, DB clients and Printers are the biggest dependencies.
Don