I use powdered sugar to roll out my fondant and keep it from sticking. I haven't really found the right way to get all the sugar off, though. Any suggestions on how to clean off my fondant decorations so they don't look ashy?

Easy. Stop rolling out the fondant on powdered sugar.
A thin - thin - film of veg shortening on your rolling surface works better.

You can rub vegetable shortening all over the cake and wipe it off with a paper towel.

I usually just spray the counter with a thin coat of Baker's Joy with flour spray.