Slipping the first stitch creates a smooth selvage edge. The stitch has to stretch up to the next row, which makes it tighter. I knit really loosely, and when doing stockinette I usually slip the first stitch so the edges aren't all wonky.
I needlefelt the beads into a rough sphere shape, then wet felt them with my hands. I get a really dense, almost perfect ball this way. I stick a pin through the center as they dry, or else it's hard to get wire through them later. Hope this helps.