The extra wooden bits on top are for reinforcement because of the motor. The original okoume floor boards are quite thin and not very strong, mine started developing cracks on the third floor board after riding it hard just once.
Do you have the side pieces for the floor?
Yes you need a drain plug, you can make one if you are handy or order one off the net somewhere, should be no problem in the states.
Drain Plug, Transom, Expanding Flip-Up 7/8" or 1"
