No, it doesn't need any glue, it's just clips and one or two screws. It's actually fairly simple to put together though looks a bit daunting to start with.
I find the focussing is actually fairly accurate, given the limitations of the lens anyway. The vignetting is really heavy, but the centres in my pics are generally quite nicely in focus. I took my aperture ring out (and, er, lost it) which makes the vignetting even more extreme - but it's nice for single-subject pics and close-ups. The birdbath pic is with the ring, the coot is without.