Starcraft renovations?

[animal]

Once it gets a lil colder out(I'm in RI,there's still some good fishing ahead),I'll pull the seats,and floor.The floor,I'll replace,as it's a shoddy job,using osb.My plan is to put pink styro insulation under the new floor,leaving room for bilge water to escape.
Not having done this before,do you paint the plywood on all sides,or what,to seal it?I'm thinking of carpetting it,which will hold moisture,so I know I've gotta seal it pretty well.What should I use?
After the floors done,my tentative plan is to build new seats.I'd like to lose the second seat,for more room,and put storage boxes/benches along the gunnels from the rear seat,to the(currently)third.I figure the benches will add some stability,since removing the second seat will cost me some.
The seats I DO build,will be hinge topped for storage,and my plan is to frame them(attached)to the new floor,as the current seats flex a little in the middle in bumpy water,and the steel float boxes actually bounce up and down,actually touching the hull.I'm hoping that hard framing to the floor will alleviate this.
I figure I should paint the inside of the hull before installing the new floor,epoxy paint has been suggested,but I'll take any other suggestions as well.Same with the exterior.
I'm open to any and all advice/suggestions. Thanks in advance,guys,Bobby.