Hi JoJo -
I'm FAR from an expert, but have you tried playing with the top tension? For shredding, I would wonder if your top tension is too tight. Superior recommends loosening your top tension considerable when FMQ with all of their threads and I've found in my own experience that I generally have to loosen the top for other threads, too, when FMQ. When piecing, I move the top tension back to the regular value and that works well.
As for the nests, I don't generally get them at the beginning of my quilting if I've pulled the bobbin thread taut so there is not extra play down there. But I have gotten them periodically in the middle of my quilting and that seems to be from the bobbin suddenly spinning out of control. I would suggest begin careful to start slow and build up your speed at a constant pace and maybe get some magic genie washers to put in your bobbin case. I use those on my machines and am not certain that they help for me, but several well-known quilters swear by them (Leah Day and Patsy Thompson, off the top of my head). According to Leah, then work in drop in bobbins, although I've not tried that since I have a front-loading bobbin myself.
Hope some of this helps,
Nancy