There is a channel under the "seat" portion, which in turn drains into the seat "base" which typically has drain holes drilled in the "lowest" channel around the perimeter of the interior of the base. Sometimes these drain holes are not drilled or not drilled completely through. This is can be easily fixed by your dealer. It's not a design flaw. There are 10's of thousands of Benningtons with this design and a very select few with the water draining issue. Remember, after a rain, there is an inherent nature for water to end up in the seats. They are not designed to be water proof.
Second, as for the seat closing, it will take a little getting used to how the Bennington seats close. They don't just flop shut like other brands. The seats have an overhang so if that bracket wasn't there, the seat would flop open if you sat on the edge of the seat. I use my left hand to guide the rear of the cushion with bracket under the rear lip, and lift front slightly, and push ack and down to close with my right hand.