Hi Gila!
Yes, you do want to still ice the cake. I normally do a little more than a standard crumb coat, but much less than if I was not using fondant. Generally, just enough to make it stick. If you use too much, it can squish out of the bottom. If you are using a crusting buttercream, let it crust and then slightly mist it with water before placing the fondant on top. If you are using a meringue based buttercream, put the iced cake in the fridge for a little bit to let it harden up. Once hardened, mist with water and apply fondant. You do want the BC to be relatively smooth, but it doesn't have to be perfect. There are some great videos on how to apply fondant as well. One trick that I have picked up is the have the cake lifted up off the counter, letting the fondant fall below it. Once you have smoothed it down all of the sides, you just use a knife to cut off the excess. It creates a very smooth line at the bottom. HTH and hopefully more people can give you some more tips and tricks as well.
Have fun!
Amber
I'll second Amber on that one. I use more BC than a crumb coat but less than if I were icing the cake solely in BC. The fondant has to stick to something. There are Youtube videos about using fondant, but if you can manage it, I would HIGHLY recommend Sugarshack's fondant DVD. I bought it, and I love it. you can order it from Sugared Productions.
Yes you do put a thin layer of icing on your cake before the fondant. It is called a crumb coat. It will help smooth out an imperfections in the cake and help you move the fondant around, a make for a smooth look on your fondant. But it is a "thin" layer of icing. Don't make my newbie mistake and put to much on 
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