When determining the Prevailing Wage and PWCMW rates, are fringe benefits added to to the hourly rate?

Yes.

In calculating the Prevailing Wage rate, the department will continue to factor in fringe benefits as spelled out in Sec. 290.210 RSMo.

The PWCMW is calculated by multiplying the average hourly wage number (developed by the Missouri Department of Economic Development) by 120%.  The extra 20% added to the average wage by this formula is used to estimate a fringe benefit for workers in that county.