Glue up the trim on the end, first. Do a dry fit, first, then as you take it apart lay everything where you can easily reach it as you put it back together again, after adding the glue. To help keep the edge piece aligned, I clamped a pair of hardboard scraps at each end. I used the piece of doubled MDF I'd cut off the end as a cawl, to help spread the pressure of the clamps. Squeeze some glue into a small bowl, and use a disposable brush. As you clamp down, position the trim just a little bit proud of the top surface.
While a strict figure for the bench’s weight capacity is not available, a quick browse through their other stand and bench products shows a general weight capacity well above most other brands. As such, while we cannot say for certain that this bench provides the best weight capacity, it is more than likely that it the capacity is similar to the other products in the catalog.