I'm anxious to see it done. Others gave you great advice. A walking foot really helps when machine quilting. It really saves on the frustration of shifting layers.
Stitch in the ditch is following exactly down your seam lines. There is a foot that has a little blade that sticks straight down that makes it easy to ride right down that seam but (to my knowledge) doesn't come as a walking foot so it is a trade. You need to figure out what works best for you. As with anything it takes practice practice practice.
Also, I use machingers but there are other things out there. They are a glove with rubber finger tips which helps grip the quilt as I am moving it around.
Quiltinlee said pins every 2 inches. Don't skimp on this. That is what helps keep those nasty wrinkles away.