If you have a good machine quilter- you can just have her/him quilt it down- but my preference is to machine appliqué them before quilting it.
I like to put a "blanket" stitch on the edge. But there is... a satin stitch or a zig zag too.
It is easier to do the appliqué prior to piecing it to your quilt top.
I think putting your little trees on the sides would be really cute. do one per block and add to your sides...does this make sense? You could even add another canoe or a few fish. Good Luck!