Fabric Questions....

I went fabric shopping today, looking for background, but realized I had some questions before I could buy.  I am wondering...
1.  Do you cut your background squares extra large to allow for shrink up from the stitching, since these blocks are heavily appliqued, and if so, how much larger?  Say on a 15 inch finished block, how large do you cut it?  (I ask because I have had blocks shrink a bunch when I applique--maybe I am pulling too tightly?)
2.  Is the normal 1/2 inch seam allowance the amount that is called for in the pattern (and thus fabric requirements)?
3.  For anyone making the Roseville quilt, was the 9.5 yards recommended on Glorious Color for the background plenty of fabric or did you have a bit extra left? 

I'm just trying to guess how much extra to buy to be safe and have it all match.  I haven't gotten the pattern yet, but wanted to have an idea if I find some fabric this next weekend as I'll be able to shop a couple stores out of my area, and still won't have the pattern when I'm able to shop.  Hope that makes sense--I'd appreciate your advice.