On covering your yurt: To do this in a way that you'll end up smiling, you need to ask yourself what you're gonna use your yurt for. Will it be a semi-permanent spare room in your yard? Or do you plan to take it to weekend events and camp? How setting-correct does it have to be?
Someone suggested used billboard skins. They're heavy and they don't breath. But they are relatively cheap, and not an altogether sucky choice for a fixed structure. You can band them on as-is, (like any flat-panel roof tarp) and hide the folds in the back of the ger if it matter to ya. For a fitted roof, you can cut the folds and glue or heat-weld the seam with a hot-air tool for PCV membrane roofing.
Then there's canvas. It's more expensive, and more work. But I think it's a better choice for a mobile camping yurt. Sunforger is a good choice- I use the 10.10 oz., but lotsa folks like the 12 oz. too. It's lighter, breathes better, and the light color helps keep the tent cooler in the summer. You'll need a canvas-capable sewing machine, and the burliest cotton-wrapped poly thread your machine can handle. Making good seams is available lotsa places on the 'net. Be wary in your planning though- even pre-shrunk Sunforger will shrink a little more once wet.
And then there's the third option: white plastic tarp. Even cheaper, light, compact, and totally rain-proof, I've skinned "budget yurts" with this stuff before. I know it's not "authentic", but it works. And in white, it doesn't look
that bad. The only real down sides are again, breathability (ventilate as necessary), and the horrifying racket that accompanies serious rain or hail. Best of luck, fellow yurt-monger!
Cheers-
Alchamar