Brasso, you need to roll your fondant out to about 5mm thick . Knead it well so it's about body temperature but not horrible goopy. Then, keep it moving as you roll out. So, go forwards and backwards once, spin it 90 degrees, go forwards and backwards again, spin it 90 degrees, etc. Also lift every 3rd or 4th turn and sprinkle a little bit more icing sugar underneath. Keeping it moving and turning it all the time means it will be more evenly rolled too - you won't have fat bits and thin bits! If it starts to go a peculiar shape then bash it back into a square with the heel/side of your hand before you roll again. Once it's the right thickness fold it over the rolling pin, drape it over the cake and smooth with your hands first, easing out the big creases. Use the palm of your hand to rub the corners otherwise you'll get awful cracks.
If you tell us how big the cake is I can tell you how much icing you'll need to get a god covering.
I would cover the blocks in the same way as you cover the main cake, tbh.
I agree with stealth, too. A plain iced cake is very hard to achieve if you're a novice. Go with a design where you can stick some kind of decoration over any major flaws .
PLUM, I get my boards and boxes in bulk from thecraftcompany.co.uk. They're the cheapest for the actual items and their postage is very reasonable too (to England, at least, don't know about for you). I found quite a few places where the boxes/boards were really cheap but the postage was so extortionate it almost doubled the price of each one.
Have finished one dummy wedding cake, the other is plain iced, just waiting for its stencilling. MIL's 60th cake is nearly finished and I've made all the wired flowers for it. Just got to ice the top tier and assemble it now......
I think I'll have to link to my FB fan page because I can't get DH's laptop to reduce the size of the pics (bloomin' MacBook). Will do it when I've finished this week's orders.