Cypress suggests all its customers to use the CyUSB.dll for all new designs. CyUSB.inf points to the CyUSB.sys driver which is the driver recommended for all new designs. The driver is available as part of SuiteUSB package. The SuiteUSB package can be downloaded from the link https://secure.cypress.com/?rID=34870.
It also has a template C# project in the path "Cypress Suite USB 3.4.x\CyUSB.NET\examples\Template", on which one’s own custom host application can be developed. x is the version number of SuiteUSB package.
Also, going through the Programmer’s guide to C# library in the path "Cypress Suite USB 3.4.x\CyUSB.NET\CyUSB.NET.pdf". This should be a good starting point to build one’s own host application.