Earlier in your W.I.P. you asked about ways to create the spiral slide. Even though you did an excellent job, here's another method you could try for future projects. All I did was create a cylinder, use a twist deformer then extrude a column of faces outward (twice to create row of faces I could make the side wall from). Then I extruded the outer faces upward to create the side wall. A few more extrudes and some minor tweaking later, you end up with a decent start.