Rhino Engine noise
When you have the windshield on it and you are in dusty conditions, the dust wants to wrap arpund the windshield and blow into the face of you, and your passengers, if any. I read about this in the issue of dirt wheels when they reviewed the rhino, and they had the same problem with dust that you are having.
As far as the engine noise goes, the only reason you can hear so much noise on the rhino is cause there is virtually nothing to deaden the noise. Since it is the same engine as the grizzly, the grizzly is actually a little bit quieter than the rhino cause there is more covering the engine on the grizz.
To solve the speed problem, get a cdi out of a grizz, and take the stock rhino one off. The stock speed on the Rhino is about 35 yes?? With the grizz cdi, you can go about 50-55. The dirt wheels crew also did this in their test of the rhino.
Hope this helps,