You can pin or baste a towel to the edge of the quilt so you have enough to hold the quilt in place. There are edge hoops you can buy, but this always worked for me.
I end my stitching the same way I started, with a small knot. I bury it between the layers. I also wiggle my needle in the batting to kind of tangle up some fibers. I think it helps keep the knot from popping out.
Janet