When I've machine appliqued, use the lightest possible fusible (as it'll stiffen your quilt in those areas). I probably do my prep for my material differently than most. I actually cut out all my applique pieces then place them on the fusible and put my teflon sheet on top and iron all at once, then cut out the pieces individually and haven't had a problem with fraying. I don't feel its necessary to use a stabilizer.
I also use a satin stitch. Practice with this, you don't want it too tight of stitch or it'll pucker the fabric and the width is actually a preference. I don't do my stitches very wide I go for a more thin just edging.
I make a sandwich and start adjusting my stitches every 1- 1.5" for the width and then do the same for the length of stitch to come up with the combo that I like.
Good Luck!!