I always preshrink all my fabric. I buy from different stores and the brands might shrink at different rates. Plus you never know when a fabric might bleed - I have been surprised sometimes - and you need to get the extra colour out. Otherwise it could ruin the quilt when it gets washed.

I do try to wash everything. It sort of 'levels the playing field" for the fabrics that go into a quilt, and then you don't have to wonder how the fabrics will react together, or shrink differently. I've heard people say they SHOULD have washed the fabrics first, because something had happened when the quilt was washed, but I've never heard anyone say they wished they hadn't washed the fabric first!
After I wash it, I don't iron it right away, so I can tell which had been washed and which hasn't. And I use Mary Ellen's Best Press, too. Takes the wrinkles right out!

I prewash to preshrink. The batting you use will consistently shrink, where your fabric may shrink to different degrees.

I put so much time into some of these quilts that I don't want to take ANY chances...

I do pretty simular. I wash in the gentle cycle, no detergent and then dry. I also just fold the fabric until I'm ready to use. I do starch, but only after I have my pieces cut, as it's easier for me to sew then once they have a slight stiffness to them.

I do prewash my fabrics to remove the chemicals. My hands get tiny itchy bumps if I don't prewash. Also I prefer to pre shrink my fabrics so that my finished project won't shrink so much. I also preshrink my batting if I am using a cotton batt.

If I am going to start the project right away I do HEAVILY starch my fabrics and press my fabrics. I think I get much cleaner cuts and the fabric is easier to work with when it has some body to it.

If they are fabrics for the stash I wait to wash them when I am ready to use them.